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/board/freescale/mpc8313erdb/sdram.c b/board/freescale/mpc8313erdb/sdram.c
index c8e30a0..5874e1a 100644
--- a/board/freescale/mpc8313erdb/sdram.c
+++ b/board/freescale/mpc8313erdb/sdram.c
@@ -8,6 +8,7 @@
  */
 
 #include <common.h>
+#include <init.h>
 #include <mpc83xx.h>
 #include <spd_sdram.h>