bnxt_en: Fix invalid max channel parameter in ethtool -l.

When there is only 1 MSI-X vector or in INTA mode, tx and rx pre-set
max channel parameters are shown incorrectly in ethtool -l.  With only 1
vector, bnxt_get_max_rings() will return -ENOMEM.  bnxt_get_channels
should check this return value, and set max_rx/max_tx to 0 if it is
non-zero.
Signed-off-by: Satish Baddipadige <sbaddipa@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -327,7 +327,11 @@ static void bnxt_get_channels(struct net_device *dev,
 	bnxt_get_max_rings(bp, &max_rx_rings, &max_tx_rings, true);
 	channel->max_combined = max_rx_rings;
 
-	bnxt_get_max_rings(bp, &max_rx_rings, &max_tx_rings, false);
+	if (bnxt_get_max_rings(bp, &max_rx_rings, &max_tx_rings, false)) {
+		max_rx_rings = 0;
+		max_tx_rings = 0;
+	}
+
 	tcs = netdev_get_num_tc(dev);
 	if (tcs > 1)
 		max_tx_rings /= tcs;