Export is_mem_free() function

The is_mem_free() function used to be local to bl_common.c.
This patch exports it so that it can be used outside of bl_common.c.

Change-Id: I01dcb4229f3a36f56a4724b567c5e6c416dc5e98
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
diff --git a/include/common/bl_common.h b/include/common/bl_common.h
index 12d5036..5076dfd 100644
--- a/include/common/bl_common.h
+++ b/include/common/bl_common.h
@@ -361,6 +361,9 @@
  ******************************************************************************/
 size_t image_size(unsigned int image_id);
 
+int is_mem_free(uintptr_t free_base, size_t free_size,
+		uintptr_t addr, size_t size);
+
 #if LOAD_IMAGE_V2
 
 int load_image(unsigned int image_id, image_info_t *image_data);