plat/arm: Mark arm platform initialization functions

Mark the initialization functions found in the BL31 boot sequence
as __init so they can be reclaimed when no longer needed.

Change-Id: I687a89346419c7710ef5097feaa325d83c527697
Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
diff --git a/plat/arm/board/fvp/fvp_bl31_setup.c b/plat/arm/board/fvp/fvp_bl31_setup.c
index ea11708..1c8804f 100644
--- a/plat/arm/board/fvp/fvp_bl31_setup.c
+++ b/plat/arm/board/fvp/fvp_bl31_setup.c
@@ -10,8 +10,8 @@
 #include <smmu_v3.h>
 #include "fvp_private.h"
 
-void bl31_early_platform_setup2(u_register_t arg0, u_register_t arg1,
-		u_register_t arg2, u_register_t arg3)
+void __init bl31_early_platform_setup2(u_register_t arg0,
+		u_register_t arg1, u_register_t arg2, u_register_t arg3)
 {
 	arm_bl31_early_platform_setup((void *)arg0, arg1, arg2, (void *)arg3);