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/x86/cpu/ivybridge/sdram_nop.c b/arch/x86/cpu/ivybridge/sdram_nop.c
index c55213c..54e6acf 100644
--- a/arch/x86/cpu/ivybridge/sdram_nop.c
+++ b/arch/x86/cpu/ivybridge/sdram_nop.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <init.h>
 
 DECLARE_GLOBAL_DATA_PTR;