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/stack.c b/arch/arm/lib/stack.c
index c89a219..96a248c 100644
--- a/arch/arm/lib/stack.c
+++ b/arch/arm/lib/stack.c
@@ -11,6 +11,7 @@
  * Marius Groeger <mgroeger@sysgo.de>
  */
 #include <common.h>
+#include <init.h>
 
 DECLARE_GLOBAL_DATA_PTR;