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/T208xRDB.h b/include/configs/T208xRDB.h
index 619b287..70eafc3 100644
--- a/include/configs/T208xRDB.h
+++ b/include/configs/T208xRDB.h
@@ -11,6 +11,8 @@
 #ifndef __T2080RDB_H
 #define __T2080RDB_H
 
+#include <linux/stringify.h>
+
 #define CONFIG_ICS307_REFCLK_HZ 25000000  /* ICS307 ref clk freq */
 #define CONFIG_FSL_SATA_V2