common: Drop linux/delay.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/hisilicon/hikey/hikey.c b/board/hisilicon/hikey/hikey.c
index df0f110..6eea939 100644
--- a/board/hisilicon/hikey/hikey.c
+++ b/board/hisilicon/hikey/hikey.c
@@ -15,6 +15,7 @@
 #include <netdev.h>
 #include <asm/io.h>
 #include <usb.h>
+#include <linux/delay.h>
 #include <power/hi6553_pmic.h>
 #include <asm-generic/gpio.h>
 #include <asm/arch/dwmmc.h>