rp2350: Clear shared boot data in BL2 post init

For this platform, BL2 is the first stage of the TF-M boot process. The
shared buffer used between the bootloader and runtime must be cleared
after each reset or reboot. This prevents residual state from
previous boots from affecting subsequent boot measurement related checks
performed in function `boot_add_data_to_shared_area`.

Signed-off-by: Mudit Sharma <mudit.sharma@arm.com>
Change-Id: Ic5856ccabb84538643da190d3d33e1d38cb0c0a7

Author: muditsharmaa-arm

platform/ext/target/rpi/rp2350/bl2/boot_hal_bl2.c

@@ -3,10 +3,11 @@
  * SPDX-FileCopyrightText: Copyright The TrustedFirmware-M Contributors
  */
 
-#include "boot_hal.h"
-
 #include <string.h>
+
+#include "boot_hal.h"
 #include "bl2_image_id.h"
+#include "tfm_plat_shared_measurement_data.h"
 
 bool boot_platform_should_load_image(uint32_t image_id)
 {
@@ -18,3 +19,12 @@ bool boot_platform_should_load_image(uint32_t image_id)
 
     return true;
 }
+
+int32_t boot_platform_post_init(void)
+{
+    /* Clear boot data area */
+    memset((void *)tfm_plat_get_shared_measurement_data_base(), 0,
+           tfm_plat_get_shared_measurement_data_size());
+
+    return 0;
+}