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/imx8mn_evk.h b/include/configs/imx8mn_evk.h
index 395ddf5..a07440c 100644
--- a/include/configs/imx8mn_evk.h
+++ b/include/configs/imx8mn_evk.h
@@ -7,6 +7,7 @@
 #define __IMX8MN_EVK_H
 
 #include <linux/sizes.h>
+#include <linux/stringify.h>
 #include <asm/arch/imx-regs.h>
 
 #ifdef CONFIG_SECURE_BOOT