usbip: simplify lock handling in valid_request()

The function calls spin_lock() and spin_unlock() should be in pair. This patch makes
this pairing more clear for the reader of the code.
Signed-off-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/usbip/stub_rx.c

@@ -304,18 +304,18 @@ static int stub_recv_cmd_unlink(struct stub_device *sdev,
 static int valid_request(struct stub_device *sdev, struct usbip_header *pdu)
 {
 	struct usbip_device *ud = &sdev->ud;
+	int valid = 0;
 
 	if (pdu->base.devid == sdev->devid) {
 		spin_lock(&ud->lock);
 		if (ud->status == SDEV_ST_USED) {
 			/* A request is valid. */
-			spin_unlock(&ud->lock);
-			return 1;
+			valid = 1;
 		}
 		spin_unlock(&ud->lock);
 	}
 
-	return 0;
+	return valid;
 }
 
 static struct stub_priv *stub_priv_alloc(struct stub_device *sdev,