brcmfmac: do not reconfigure refill rx on 0-length packet.

When USB device gets removed rx complete comes with 0-length
packets. Do not refill those packets. In some rare cases it can
cause infinite loop.
Reviewed-by: Arend Van Spriel <arend@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/brcm80211/brcmfmac/usb.c

@@ -467,7 +467,11 @@ static void brcmf_usb_rx_complete(struct urb *urb)
 			devinfo->bus_pub.bus->dstats.rx_errors++;
 		} else
 			brcmf_rx_packet(devinfo->dev, ifidx, skb);
-		brcmf_usb_rx_refill(devinfo, req);
+		/* zero lenght packets indicate usb "failure". Do not refill */
+		if (urb->actual_length)
+			brcmf_usb_rx_refill(devinfo, req);
+		else
+			brcmf_usb_enq(devinfo, &devinfo->rx_freeq, req, NULL);
 	} else {
 		brcmu_pkt_buf_free_skb(skb);
 		brcmf_usb_enq(devinfo, &devinfo->rx_freeq, req, NULL);