libertas: Communicate USB transfer errors

The return code was being overwritten with -1.
Useful for debugging.

Signed-off-by: Paul Fox <pgf@laptop.org>
Signed-off-by: Daniel Drake <dsd@laptop.org>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/libertas/if_usb.c

@@ -484,11 +484,12 @@ static int if_usb_reset_device(struct if_usb_card *cardp)
  */
 static int usb_tx_block(struct if_usb_card *cardp, uint8_t *payload, uint16_t nb)
 {
-	int ret = -1;
+	int ret;
 
 	/* check if device is removed */
 	if (cardp->surprise_removed) {
 		lbs_deb_usbd(&cardp->udev->dev, "Device removed\n");
+		ret = -ENODEV;
 		goto tx_ret;
 	}
 
@@ -501,7 +502,6 @@ static int usb_tx_block(struct if_usb_card *cardp, uint8_t *payload, uint16_t nb
 
 	if ((ret = usb_submit_urb(cardp->tx_urb, GFP_ATOMIC))) {
 		lbs_deb_usbd(&cardp->udev->dev, "usb_submit_urb failed: %d\n", ret);
-		ret = -1;
 	} else {
 		lbs_deb_usb2(&cardp->udev->dev, "usb_submit_urb success\n");
 		ret = 0;