common: Drop init.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/lib/spl.c b/arch/arm/lib/spl.c
index 8a24e34..5d5437c 100644
--- a/arch/arm/lib/spl.c
+++ b/arch/arm/lib/spl.c
@@ -9,6 +9,7 @@
 
 #include <common.h>
 #include <config.h>
+#include <init.h>
 #include <spl.h>
 #include <image.h>
 #include <asm/cache.h>