TF-A: Add support for Measured Boot driver

This patch adds support for Measured Boot driver functionality
in common Arm platform code.

Change-Id: If049dcf8d847c39023b77c0d805a8cf5b8bcaa3e
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
diff --git a/plat/arm/common/arm_bl2_setup.c b/plat/arm/common/arm_bl2_setup.c
index fd60c2b..80f3b32 100644
--- a/plat/arm/common/arm_bl2_setup.c
+++ b/plat/arm/common/arm_bl2_setup.c
@@ -37,6 +37,9 @@
 #pragma weak bl2_platform_setup
 #pragma weak bl2_plat_arch_setup
 #pragma weak bl2_plat_sec_mem_layout
+#if MEASURED_BOOT
+#pragma weak bl2_plat_get_hash
+#endif
 
 #define MAP_BL2_TOTAL		MAP_REGION_FLAT(			\
 					bl2_tzram_layout.total_base,	\
@@ -225,3 +228,11 @@
 {
 	return arm_bl2_plat_handle_post_image_load(image_id);
 }
+
+#if MEASURED_BOOT
+/* Read TCG_DIGEST_SIZE bytes of BL2 hash data */
+void bl2_plat_get_hash(void *data)
+{
+	arm_bl2_get_hash(data);
+}
+#endif