xen-netback: Don't deschedule NAPI when carrier off

In the patch called "xen-netback: Turn off the carrier if the guest is not able
to receive" NAPI was descheduled when the carrier was set off. That's
not what most of the drivers do, and we don't have any specific reason to do so
as well, so revert that change.

Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/xen-netback/interface.c

@@ -78,12 +78,8 @@ int xenvif_poll(struct napi_struct *napi, int budget)
 	/* This vif is rogue, we pretend we've there is nothing to do
 	 * for this vif to deschedule it from NAPI. But this interface
 	 * will be turned off in thread context later.
-	 * Also, if a guest doesn't post enough slots to receive data on one of
-	 * its queues, the carrier goes down and NAPI is descheduled here so
-	 * the guest can't send more packets until it's ready to receive.
 	 */
-	if (unlikely(queue->vif->disabled ||
-		     !netif_carrier_ok(queue->vif->dev))) {
+	if (unlikely(queue->vif->disabled)) {
 		napi_complete(napi);
 		return 0;
 	}