Add PoC of Arm DRTM specification version Beta-0

Change-Id: I26e6f2d4b2299edc246f5e8504d5d15b1399f640
diff --git a/include/plat/common/platform.h b/include/plat/common/platform.h
index 1def86e..dc16ce1 100644
--- a/include/plat/common/platform.h
+++ b/include/plat/common/platform.h
@@ -63,6 +63,7 @@
 uintptr_t plat_get_ns_image_entrypoint(void);
 unsigned int plat_my_core_pos(void);
 int plat_core_pos_by_mpidr(u_register_t mpidr);
+unsigned int plat_is_my_cpu_primary(void);
 int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size);
 
 #if STACK_PROTECTOR_ENABLED