usb: dwc2: cleanup with list_first_entry_or_null()

The combo of list_empty() check and return list_first_entry()
can be replaced with list_first_entry_or_null().

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc2/gadget.c

@@ -1099,10 +1099,8 @@ static int dwc2_hsotg_ep_sethalt(struct usb_ep *ep, int value, bool now);
  */
 static struct dwc2_hsotg_req *get_ep_head(struct dwc2_hsotg_ep *hs_ep)
 {
-	if (list_empty(&hs_ep->queue))
-		return NULL;
-
-	return list_first_entry(&hs_ep->queue, struct dwc2_hsotg_req, queue);
+	return list_first_entry_or_null(&hs_ep->queue, struct dwc2_hsotg_req,
+					queue);
 }
 
 /**