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/drivers/clk/rockchip/clk_rk3368.c b/drivers/clk/rockchip/clk_rk3368.c
index f0a72f1..34466b8 100644
--- a/drivers/clk/rockchip/clk_rk3368.c
+++ b/drivers/clk/rockchip/clk_rk3368.c
@@ -21,6 +21,7 @@
 #include <asm/io.h>
 #include <dm/lists.h>
 #include <dt-bindings/clock/rk3368-cru.h>
+#include <linux/stringify.h>
 
 #if CONFIG_IS_ENABLED(OF_PLATDATA)
 struct rk3368_clk_plat {