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/MPC8641HPCN.h b/include/configs/MPC8641HPCN.h
index e97d780..edbeeef 100644
--- a/include/configs/MPC8641HPCN.h
+++ b/include/configs/MPC8641HPCN.h
@@ -15,6 +15,8 @@
 #ifndef __CONFIG_H
 #define __CONFIG_H
 
+#include <linux/stringify.h>
+
 /* High Level Configuration Options */
 #define CONFIG_LINUX_RESET_VEC	0x100	/* Reset vector used by Linux */
 #define CONFIG_ADDR_MAP		1	/* Use addr map */