usb: mtu3: cleanup with list_first_entry_or_null()

The combo of list_empty() and list_first_entry() can be replaced with
list_first_entry_or_null().
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/mtu3/mtu3.h

@@ -356,12 +356,8 @@ static inline struct mtu3_ep *to_mtu3_ep(struct usb_ep *ep)
 
 static inline struct mtu3_request *next_request(struct mtu3_ep *mep)
 {
-	struct list_head *queue = &mep->req_list;
-
-	if (list_empty(queue))
-		return NULL;
-
-	return list_first_entry(queue, struct mtu3_request, list);
+	return list_first_entry_or_null(&mep->req_list, struct mtu3_request,
+					list);
 }
 
 static inline void mtu3_writel(void __iomem *base, u32 offset, u32 data)