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_rk3288.c b/drivers/clk/rockchip/clk_rk3288.c
index 762c9d4..b4514bc 100644
--- a/drivers/clk/rockchip/clk_rk3288.c
+++ b/drivers/clk/rockchip/clk_rk3288.c
@@ -25,6 +25,7 @@
 #include <dm/uclass-internal.h>
 #include <linux/err.h>
 #include <linux/log2.h>
+#include <linux/stringify.h>
 
 DECLARE_GLOBAL_DATA_PTR;