[hw/ip] Move local register generator

Move helper functions to a `util` folder.
diff --git a/hw/ip/alert_handler/doc/reg_alert_handler.py b/hw/ip/alert_handler/util/reg_alert_handler.py
similarity index 100%
rename from hw/ip/alert_handler/doc/reg_alert_handler.py
rename to hw/ip/alert_handler/util/reg_alert_handler.py
diff --git a/hw/ip/padctrl/doc/reg_padctrl.py b/hw/ip/padctrl/util/reg_padctrl.py
similarity index 100%
rename from hw/ip/padctrl/doc/reg_padctrl.py
rename to hw/ip/padctrl/util/reg_padctrl.py
diff --git a/hw/ip/pinmux/doc/reg_pinmux.py b/hw/ip/pinmux/util/reg_pinmux.py
similarity index 100%
rename from hw/ip/pinmux/doc/reg_pinmux.py
rename to hw/ip/pinmux/util/reg_pinmux.py
diff --git a/hw/ip/prim/script/get-lfsr-coeffs.py b/hw/ip/prim/util/get-lfsr-coeffs.py
similarity index 100%
rename from hw/ip/prim/script/get-lfsr-coeffs.py
rename to hw/ip/prim/util/get-lfsr-coeffs.py
diff --git a/hw/ip/prim/script/secded_gen.py b/hw/ip/prim/util/secded_gen.py
similarity index 100%
rename from hw/ip/prim/script/secded_gen.py
rename to hw/ip/prim/util/secded_gen.py
diff --git a/hw/ip/rv_plic/doc/reg_rv_plic.py b/hw/ip/rv_plic/util/reg_rv_plic.py
similarity index 100%
rename from hw/ip/rv_plic/doc/reg_rv_plic.py
rename to hw/ip/rv_plic/util/reg_rv_plic.py
diff --git a/hw/ip/rv_timer/doc/reg_timer.py b/hw/ip/rv_timer/util/reg_timer.py
similarity index 100%
rename from hw/ip/rv_timer/doc/reg_timer.py
rename to hw/ip/rv_timer/util/reg_timer.py