usb: musb: gadget: fix list_head usage

commit ad1adb89a0d9410345d573b6995a1fa9f9b7c74a
(usb: musb: gadget: do not poke with gadget's list_head)
fixed a bug in musb where it was corrupting the list_head
which is supposed to be used by gadget drivers. While
doing that, I forgot to fix the usage in musb_gadget_dequeue()
method. Fix that.

Reported-by: Pavol Kurina <pavol.kurina@emsys.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_gadget.c

@@ -1274,7 +1274,8 @@ cleanup:
 static int musb_gadget_dequeue(struct usb_ep *ep, struct usb_request *request)
 {
 	struct musb_ep		*musb_ep = to_musb_ep(ep);
-	struct usb_request	*r;
+	struct musb_request	*req = to_musb_request(request);
+	struct musb_request	*r;
 	unsigned long		flags;
 	int			status = 0;
 	struct musb		*musb = musb_ep->musb;
@@ -1285,10 +1286,10 @@ static int musb_gadget_dequeue(struct usb_ep *ep, struct usb_request *request)
 	spin_lock_irqsave(&musb->lock, flags);
 
 	list_for_each_entry(r, &musb_ep->req_list, list) {
-		if (r == request)
+		if (r == req)
 			break;
 	}
-	if (r != request) {
+	if (r != req) {
 		DBG(3, "request %p not queued to %s\n", request, ep->name);
 		status = -EINVAL;
 		goto done;