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/common/usb.c b/common/usb.c
index 7c60460..aad13fd 100644
--- a/common/usb.c
+++ b/common/usb.c
@@ -38,6 +38,7 @@
 #include <asm/unaligned.h>
 #include <errno.h>
 #include <usb.h>
+#include <linux/delay.h>
 
 #define USB_BUFSIZ	512