refactor(bl2): make post image handling platform-specific

In certain instances a platform may need to make modifications to an
image after it has been loaded by BL2. The existing common
implementation is a thin wrapper for a more generic arm post image
handler. To enable platforms to make changes to images when
they're loaded, move this into platform code.

Change-Id: I44025391056adb2d8a8eb4ea5984257b02027181
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
diff --git a/plat/arm/board/fvp_ve/fvp_ve_bl2_setup.c b/plat/arm/board/fvp_ve/fvp_ve_bl2_setup.c
index 4ccae27..cc29f36 100644
--- a/plat/arm/board/fvp_ve/fvp_ve_bl2_setup.c
+++ b/plat/arm/board/fvp_ve/fvp_ve_bl2_setup.c
@@ -39,3 +39,8 @@
 	generic_delay_timer_init();
 #endif /* USE_SP804_TIMER */
 }
+
+int bl2_plat_handle_post_image_load(unsigned int image_id)
+{
+	return arm_bl2_plat_handle_post_image_load(image_id);
+}