Mark BL31 initialization functions

Mark the initialization functions in BL31, such as context management,
EHF, RAS and PSCI as __init so that they can be reclaimed by the
platform when no longer needed

Change-Id: I7446aeee3dde8950b0f410cb766b7a2312c20130
Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
diff --git a/bl31/ehf.c b/bl31/ehf.c
index 3d6d674..fa036cb 100644
--- a/bl31/ehf.c
+++ b/bl31/ehf.c
@@ -451,7 +451,7 @@
 /*
  * Initialize the EL3 exception handling.
  */
-void ehf_init(void)
+void __init ehf_init(void)
 {
 	unsigned int flags = 0;
 	int ret __unused;