[rtl] Change reg instance name to i_reg

Apply this change to all IPs for backdoor access support.
Refer to #2406 for detail

Signed-off-by: Weicai Yang <weicai@google.com>
diff --git a/hw/ip/aes/rtl/aes.sv b/hw/ip/aes/rtl/aes.sv
index 6aca830..2c03b5f 100644
--- a/hw/ip/aes/rtl/aes.sv
+++ b/hw/ip/aes/rtl/aes.sv
@@ -39,7 +39,7 @@
   logic        prng_reseed_req;
   logic        prng_reseed_ack;
 
-  aes_reg_top aes_reg_top (
+  aes_reg_top u_reg (
     .clk_i,
     .rst_ni,
     .tl_i,
diff --git a/hw/ip/alert_handler/rtl/alert_handler_reg_wrap.sv b/hw/ip/alert_handler/rtl/alert_handler_reg_wrap.sv
index e795ee4..f6dbdde 100644
--- a/hw/ip/alert_handler/rtl/alert_handler_reg_wrap.sv
+++ b/hw/ip/alert_handler/rtl/alert_handler_reg_wrap.sv
@@ -29,7 +29,7 @@
   alert_handler_reg_pkg::alert_handler_reg2hw_t reg2hw;
   alert_handler_reg_pkg::alert_handler_hw2reg_t hw2reg;
 
-  alert_handler_reg_top i_reg (
+  alert_handler_reg_top u_reg (
     .clk_i,
     .rst_ni,
     .tl_i,
diff --git a/hw/ip/clkmgr/data/clkmgr.sv.tpl b/hw/ip/clkmgr/data/clkmgr.sv.tpl
index 176c3d4..cc01030 100644
--- a/hw/ip/clkmgr/data/clkmgr.sv.tpl
+++ b/hw/ip/clkmgr/data/clkmgr.sv.tpl
@@ -52,7 +52,7 @@
   clkmgr_reg_pkg::clkmgr_reg2hw_t reg2hw;
   clkmgr_reg_pkg::clkmgr_hw2reg_t hw2reg;
 
-  clkmgr_reg_top i_reg (
+  clkmgr_reg_top u_reg (
     .clk_i,
     .rst_ni,
     .tl_i,
diff --git a/hw/ip/clkmgr/rtl/clkmgr.sv b/hw/ip/clkmgr/rtl/clkmgr.sv
index f143e3e..8d8a0ea 100644
--- a/hw/ip/clkmgr/rtl/clkmgr.sv
+++ b/hw/ip/clkmgr/rtl/clkmgr.sv
@@ -45,7 +45,7 @@
   clkmgr_reg_pkg::clkmgr_reg2hw_t reg2hw;
   clkmgr_reg_pkg::clkmgr_hw2reg_t hw2reg;
 
-  clkmgr_reg_top i_reg (
+  clkmgr_reg_top u_reg (
     .clk_i,
     .rst_ni,
     .tl_i,
diff --git a/hw/ip/entropy_src/rtl/entropy_src.sv b/hw/ip/entropy_src/rtl/entropy_src.sv
index 41ab7d8..1269dd1 100755
--- a/hw/ip/entropy_src/rtl/entropy_src.sv
+++ b/hw/ip/entropy_src/rtl/entropy_src.sv
@@ -38,7 +38,7 @@
   entropy_src_reg2hw_t reg2hw;
   entropy_src_hw2reg_t hw2reg;
 
-  entropy_src_reg_top u_entropy_src_reg_top (
+  entropy_src_reg_top u_reg (
     .clk_i,
     .rst_ni,
     .tl_i,
diff --git a/hw/ip/nmi_gen/rtl/nmi_gen.sv b/hw/ip/nmi_gen/rtl/nmi_gen.sv
index de810b4..00bf37c 100644
--- a/hw/ip/nmi_gen/rtl/nmi_gen.sv
+++ b/hw/ip/nmi_gen/rtl/nmi_gen.sv
@@ -35,7 +35,7 @@
   nmi_gen_reg_pkg::nmi_gen_reg2hw_t reg2hw;
   nmi_gen_reg_pkg::nmi_gen_hw2reg_t hw2reg;
 
-  nmi_gen_reg_top i_reg (
+  nmi_gen_reg_top u_reg (
     .clk_i,
     .rst_ni,
     .tl_i,
diff --git a/hw/ip/otp_ctrl/rtl/otp_ctrl.sv b/hw/ip/otp_ctrl/rtl/otp_ctrl.sv
index e43d034..da72b2c 100644
--- a/hw/ip/otp_ctrl/rtl/otp_ctrl.sv
+++ b/hw/ip/otp_ctrl/rtl/otp_ctrl.sv
@@ -50,7 +50,7 @@
   otp_ctrl_reg_pkg::otp_ctrl_reg2hw_t reg2hw;
   otp_ctrl_reg_pkg::otp_ctrl_hw2reg_t hw2reg;
 
-  otp_ctrl_reg_top i_otp_ctrl_reg_top (
+  otp_ctrl_reg_top u_reg (
     .clk_i ,
     .rst_ni,
     .tl_i,
diff --git a/hw/ip/padctrl/rtl/padctrl.sv b/hw/ip/padctrl/rtl/padctrl.sv
index 5d7eafa..ad0529b 100644
--- a/hw/ip/padctrl/rtl/padctrl.sv
+++ b/hw/ip/padctrl/rtl/padctrl.sv
@@ -52,7 +52,7 @@
   padctrl_reg2hw_t reg2hw;
   padctrl_hw2reg_t hw2reg;
 
-  padctrl_reg_top i_reg_top (
+  padctrl_reg_top u_reg (
     .clk_i  ,
     .rst_ni ,
     .tl_i   ,
diff --git a/hw/ip/pinmux/rtl/pinmux.sv b/hw/ip/pinmux/rtl/pinmux.sv
index 964f965..d968f66 100644
--- a/hw/ip/pinmux/rtl/pinmux.sv
+++ b/hw/ip/pinmux/rtl/pinmux.sv
@@ -64,7 +64,7 @@
   pinmux_reg2hw_t reg2hw;
   pinmux_hw2reg_t hw2reg;
 
-  pinmux_reg_top i_reg_top (
+  pinmux_reg_top u_reg (
     .clk_i  ,
     .rst_ni ,
     .tl_i   ,
diff --git a/hw/ip/pwrmgr/rtl/pwrmgr.sv b/hw/ip/pwrmgr/rtl/pwrmgr.sv
index 2edd8e7..b86cf17 100644
--- a/hw/ip/pwrmgr/rtl/pwrmgr.sv
+++ b/hw/ip/pwrmgr/rtl/pwrmgr.sv
@@ -104,7 +104,7 @@
   logic wkup;
   logic clr_cfg_lock;
 
-  pwrmgr_reg_top i_reg (
+  pwrmgr_reg_top u_reg (
     .clk_i,
     .rst_ni,
     .tl_i,
diff --git a/hw/ip/rstmgr/rtl/rstmgr.sv b/hw/ip/rstmgr/rtl/rstmgr.sv
index 76ca8a1..eb592ab 100644
--- a/hw/ip/rstmgr/rtl/rstmgr.sv
+++ b/hw/ip/rstmgr/rtl/rstmgr.sv
@@ -88,7 +88,7 @@
   rstmgr_reg_pkg::rstmgr_reg2hw_t reg2hw;
   rstmgr_reg_pkg::rstmgr_hw2reg_t hw2reg;
 
-  rstmgr_reg_top i_reg (
+  rstmgr_reg_top u_reg (
     .clk_i,
     .rst_ni(resets_o.rst_por_aon_n),
     .tl_i,
diff --git a/hw/top_earlgrey/ip/clkmgr/rtl/autogen/clkmgr.sv b/hw/top_earlgrey/ip/clkmgr/rtl/autogen/clkmgr.sv
index ca00c89..2a2f784 100644
--- a/hw/top_earlgrey/ip/clkmgr/rtl/autogen/clkmgr.sv
+++ b/hw/top_earlgrey/ip/clkmgr/rtl/autogen/clkmgr.sv
@@ -56,7 +56,7 @@
   clkmgr_reg_pkg::clkmgr_reg2hw_t reg2hw;
   clkmgr_reg_pkg::clkmgr_hw2reg_t hw2reg;
 
-  clkmgr_reg_top i_reg (
+  clkmgr_reg_top u_reg (
     .clk_i,
     .rst_ni,
     .tl_i,