hyperv: Fix a kernel warning from netvsc_linkstatus_callback()

The warning about local_bh_enable inside IRQ happens when disconnecting a
virtual NIC.

The reason for the warning is -- netif_tx_disable() is called when the NIC
is disconnected. And it's called within irq context. netif_tx_disable() calls
local_bh_enable() which displays warning if in irq.

The fix is to remove the unnecessary netif_tx_disable & wake_queue() in the
netvsc_linkstatus_callback().

Reported-by: Richard Genoud <richard.genoud@gmail.com>
Tested-by: Long Li <longli@microsoft.com>
Tested-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hyperv/netvsc_drv.c

@@ -241,13 +241,11 @@ void netvsc_linkstatus_callback(struct hv_device *device_obj,
 
 	if (status == 1) {
 		netif_carrier_on(net);
-		netif_wake_queue(net);
 		ndev_ctx = netdev_priv(net);
 		schedule_delayed_work(&ndev_ctx->dwork, 0);
 		schedule_delayed_work(&ndev_ctx->dwork, msecs_to_jiffies(20));
 	} else {
 		netif_carrier_off(net);
-		netif_tx_disable(net);
 	}
 }