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/socfpga_common.h b/include/configs/socfpga_common.h
index 0579a00..07c9745 100644
--- a/include/configs/socfpga_common.h
+++ b/include/configs/socfpga_common.h
@@ -5,6 +5,8 @@
 #ifndef __CONFIG_SOCFPGA_COMMON_H__
 #define __CONFIG_SOCFPGA_COMMON_H__
 
+#include <linux/stringify.h>
+
 /*
  * High level configuration
  */