Prevent two weak definitions of the same function

Add another level of abstraction of weak defs for
arm_bl2_handle_post_image_load to prevent two weak definitions
of the same function

Change-Id: Ie953786f43b0f88257c82956ffaa5fe0d19603db
Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
diff --git a/plat/arm/board/juno/juno_bl2_setup.c b/plat/arm/board/juno/juno_bl2_setup.c
index cedef66..1f483d6 100644
--- a/plat/arm/board/juno/juno_bl2_setup.c
+++ b/plat/arm/board/juno/juno_bl2_setup.c
@@ -16,7 +16,7 @@
  * boot flow as the core comes up in aarch64 and to enter the BL32 image a warm
  * reset in aarch32 state is required.
  ******************************************************************************/
-int bl2_plat_handle_post_image_load(unsigned int image_id)
+int arm_bl2_plat_handle_post_image_load(unsigned int image_id)
 {
 	int err = arm_bl2_handle_post_image_load(image_id);