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/tqma6.h b/include/configs/tqma6.h
index 895cd03..13ab1cc 100644
--- a/include/configs/tqma6.h
+++ b/include/configs/tqma6.h
@@ -9,6 +9,8 @@
 #define __CONFIG_H
 
 #include <linux/kconfig.h>
+#include <linux/stringify.h>
+
 /* SPL */
 /* #if defined(CONFIG_SPL_BUILD) */
 /* common IMX6 SPL configuration */