common: Drop linux/stringify.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/configs/liteboard.h b/include/configs/liteboard.h
index fa7d589..f9a125f 100644
--- a/include/configs/liteboard.h
+++ b/include/configs/liteboard.h
@@ -10,6 +10,7 @@
 
 #include <asm/arch/imx-regs.h>
 #include <linux/sizes.h>
+#include <linux/stringify.h>
 #include "mx6_common.h"
 
 /* SPL options */