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/drivers/rtc/imxdi.c b/drivers/rtc/imxdi.c
index 39920f1..e3a1393 100644
--- a/drivers/rtc/imxdi.c
+++ b/drivers/rtc/imxdi.c
@@ -16,6 +16,7 @@
 #include <command.h>
 #include <linux/compat.h>
 #include <rtc.h>
+#include <linux/delay.h>
 
 #include <asm/io.h>
 #include <asm/arch/imx-regs.h>