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/P1022DS.h b/include/configs/P1022DS.h
index e99d509..2b76107 100644
--- a/include/configs/P1022DS.h
+++ b/include/configs/P1022DS.h
@@ -8,6 +8,8 @@
 #ifndef __CONFIG_H
 #define __CONFIG_H
 
+#include <linux/stringify.h>
+
 #include "../board/freescale/common/ics307_clk.h"
 
 #ifdef CONFIG_SDCARD