bnxt_en: Remove locking around txr->dev_state

txr->dev_state was not consistently manipulated with the acquisition of
the per-queue lock, after further inspection the lock does not seem
necessary, either the value is read as BNXT_DEV_STATE_CLOSING or 0.

Reported-by: coverity (CID 1339583)
Fixes: c0c050c5 ("bnxt_en: New Broadcom ethernet driver.")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -4930,9 +4930,7 @@ static void bnxt_tx_disable(struct bnxt *bp)
 		for (i = 0; i < bp->tx_nr_rings; i++) {
 			txr = &bp->tx_ring[i];
 			txq = netdev_get_tx_queue(bp->dev, i);
-			__netif_tx_lock(txq, smp_processor_id());
 			txr->dev_state = BNXT_DEV_STATE_CLOSING;
-			__netif_tx_unlock(txq);
 		}
 	}
 	/* Stop all TX queues */