usb: mtu3: Remove unsused inline function is_first_entry

It is never used, so can be removed.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20200731082008.33016-1-yuehaibing@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/mtu3/mtu3.h

@@ -370,12 +370,6 @@ static inline struct mtu3 *gadget_to_mtu3(struct usb_gadget *g)
 	return container_of(g, struct mtu3, g);
 }
 
-static inline int is_first_entry(const struct list_head *list,
-	const struct list_head *head)
-{
-	return list_is_last(head, list);
-}
-
 static inline struct mtu3_request *to_mtu3_request(struct usb_request *req)
 {
 	return req ? container_of(req, struct mtu3_request, request) : NULL;