[sw/silicon_creator] Use memset to initialize epmp_state

This commit improves the initialization of `epmp_state` in `rom_epmp.c`
and `rom_epmp_test.c` by replacing the temporary that was initialized
and copied over with a single call to `memset`.

Signed-off-by: Alphan Ulusoy <alphan@google.com>

sw/device/silicon_creator/rom/BUILD

diff --git a/sw/device/silicon_creator/rom/BUILD b/sw/device/silicon_creator/rom/BUILD
index 914288f..f127db4 100644
--- a/sw/device/silicon_creator/rom/BUILD
+++ b/sw/device/silicon_creator/rom/BUILD
@@ -145,6 +145,7 @@
         "//hw/top_earlgrey/sw/autogen:top_earlgrey",
         "//sw/device/lib/base:bitfield",
         "//sw/device/lib/base:csr",
+        "//sw/device/lib/base:memory",
         "//sw/device/silicon_creator/lib:epmp_state",
         "//sw/device/silicon_creator/lib/drivers:lifecycle",
     ],

sw/device/silicon_creator/rom/rom_epmp.c

diff --git a/sw/device/silicon_creator/rom/rom_epmp.c b/sw/device/silicon_creator/rom/rom_epmp.c
index 9663893..b2cf46a 100644
--- a/sw/device/silicon_creator/rom/rom_epmp.c
+++ b/sw/device/silicon_creator/rom/rom_epmp.c
@@ -6,6 +6,7 @@
 
 #include "sw/device/lib/base/bitfield.h"
 #include "sw/device/lib/base/csr.h"
+#include "sw/device/lib/base/memory.h"
 
 #include "hw/top_earlgrey/sw/autogen/top_earlgrey.h"
 
@@ -85,7 +86,7 @@
   // The actual hardware configuration is performed separately, either by reset
   // logic or in assembly. This code must be kept in sync with any changes
   // to the hardware configuration.
-  epmp_state = (epmp_state_t){0};
+  memset(&epmp_state, 0, sizeof(epmp_state));
   epmp_state_configure_tor(1, rom_text, kEpmpPermLockedReadExecute);
   epmp_state_configure_napot(2, rom, kEpmpPermLockedReadOnly);
   epmp_state_configure_napot(5, eflash, kEpmpPermLockedReadOnly);

sw/device/silicon_creator/rom/rom_epmp_test.c

diff --git a/sw/device/silicon_creator/rom/rom_epmp_test.c b/sw/device/silicon_creator/rom/rom_epmp_test.c
index d583b39..dbf80b5 100644
--- a/sw/device/silicon_creator/rom/rom_epmp_test.c
+++ b/sw/device/silicon_creator/rom/rom_epmp_test.c
@@ -375,7 +375,7 @@
   LOG_INFO("Starting ROM ePMP functional test.");
 
   // Initialize shadow copy of the ePMP register configuration.
-  epmp_state = (epmp_state_t){0};
+  memset(&epmp_state, 0, sizeof(epmp_state));
   rom_epmp_state_init(kLcStateProd);
   CHECK(epmp_state_check() == kErrorOk);