feat(lib/optee): introduce optee_header_is_valid()

This new function optee_header_is_valid() allows platform to know
whether OP-TEE OS is loaded from multi-image (using OP-TEE header
image as BL32_IMAGE_ID) or from a single OP-TEE binary image.
The function tee_validate_header() is reworked to return a boolean,
and is now silent.

Change-Id: Idc7dde091f2ada8898f40d02e68c3834ca39d8e8
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>
Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
diff --git a/include/lib/optee_utils.h b/include/lib/optee_utils.h
index 6067caf..06378eb 100644
--- a/include/lib/optee_utils.h
+++ b/include/lib/optee_utils.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -7,8 +7,12 @@
 #ifndef OPTEE_UTILS_H
 #define OPTEE_UTILS_H
 
+#include <stdbool.h>
+
 #include <common/bl_common.h>
 
+bool optee_header_is_valid(uintptr_t header_base);
+
 int parse_optee_header(entry_point_info_t *header_ep,
 	image_info_t *pager_image_info,
 	image_info_t *paged_image_info);