Support shared Mbed TLS heap for SGM

Change-Id: Ibbfedb6601feff51dfb82c1d94850716c5a36d24
Signed-off-by: John Tsichritzis <john.tsichritzis@arm.com>
diff --git a/plat/arm/css/sgm/sgm_plat_config.c b/plat/arm/css/sgm/sgm_plat_config.c
index 809edf6..97b16a8 100644
--- a/plat/arm/css/sgm/sgm_plat_config.c
+++ b/plat/arm/css/sgm/sgm_plat_config.c
@@ -67,3 +67,13 @@
 	assert(css_plat_info != NULL);
 	return css_plat_info;
 }
+
+#if TRUSTED_BOARD_BOOT && LOAD_IMAGE_V2
+int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size)
+{
+	assert(heap_addr != NULL);
+	assert(heap_size != NULL);
+
+	return arm_get_mbedtls_heap(heap_addr, heap_size);
+}
+#endif