bnxt_en: Fix VLAN acceleration handling in bnxt_fix_features().

The current logic in bnxt_fix_features() will inadvertently turn on both
CTAG and STAG VLAN offload if the user tries to disable both.  Fix it
by checking that the user is trying to enable CTAG or STAG before
enabling both.  The logic is supposed to enable or disable both CTAG and
STAG together.

Fixes: 5a9f6b23 ("bnxt_en: Enable and disable RX CTAG and RX STAG VLAN acceleration together.")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -9780,6 +9780,7 @@ static netdev_features_t bnxt_fix_features(struct net_device *dev,
 					   netdev_features_t features)
 {
 	struct bnxt *bp = netdev_priv(dev);
+	netdev_features_t vlan_features;
 
 	if ((features & NETIF_F_NTUPLE) && !bnxt_rfs_capable(bp))
 		features &= ~NETIF_F_NTUPLE;
@@ -9796,12 +9797,14 @@ static netdev_features_t bnxt_fix_features(struct net_device *dev,
 	/* Both CTAG and STAG VLAN accelaration on the RX side have to be
 	 * turned on or off together.
 	 */
-	if ((features & (NETIF_F_HW_VLAN_CTAG_RX | NETIF_F_HW_VLAN_STAG_RX)) !=
-	    (NETIF_F_HW_VLAN_CTAG_RX | NETIF_F_HW_VLAN_STAG_RX)) {
+	vlan_features = features & (NETIF_F_HW_VLAN_CTAG_RX |
+				    NETIF_F_HW_VLAN_STAG_RX);
+	if (vlan_features != (NETIF_F_HW_VLAN_CTAG_RX |
+			      NETIF_F_HW_VLAN_STAG_RX)) {
 		if (dev->features & NETIF_F_HW_VLAN_CTAG_RX)
 			features &= ~(NETIF_F_HW_VLAN_CTAG_RX |
 				      NETIF_F_HW_VLAN_STAG_RX);
-		else
+		else if (vlan_features)
 			features |= NETIF_F_HW_VLAN_CTAG_RX |
 				    NETIF_F_HW_VLAN_STAG_RX;
 	}