refactor(plat/arm): mark the flash region as read-only

In the FVP platform, BL1 uses flash only for read purpose
hence marked this flash region as read-only.

Change-Id: I3b57130fd4f3b4df522ac075f66e9799f237ebb7
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>

plat/arm/board/fvp/fvp_common.c

@@ -72,14 +72,11 @@ arm_config_t arm_config;
  * Table of memory regions for various BL stages to map using the MMU.
  * This doesn't include Trusted SRAM as setup_page_tables() already takes care
  * of mapping it.
- *
- * The flash needs to be mapped as writable in order to erase the FIP's Table of
- * Contents in case of unrecoverable error (see plat_error_handler()).
  */
 #ifdef IMAGE_BL1
 const mmap_region_t plat_arm_mmap[] = {
 	ARM_MAP_SHARED_RAM,
-	V2M_MAP_FLASH0_RW,
+	V2M_MAP_FLASH0_RO,
 	V2M_MAP_IOFPGA,
 	MAP_DEVICE0,
 #if FVP_INTERCONNECT_DRIVER == FVP_CCN