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/wandboard.h b/include/configs/wandboard.h
index 9d2bd7b..2b0576e 100644
--- a/include/configs/wandboard.h
+++ b/include/configs/wandboard.h
@@ -107,6 +107,7 @@
 	func(DHCP, dhcp, na)
 
 #include <config_distro_bootcmd.h>
+#include <linux/stringify.h>
 
 /* Physical Memory Map */
 #define PHYS_SDRAM			MMDC0_ARB_BASE_ADDR