net/mlx5e: In skb build skip setting mark in switchdev mode

sop_drop_qpn field in the cqe is used by two features, in SWITCHDEV mode
to restore the chain id in case of a miss and in LEGACY mode to support
skbedit mark action. In build RX skb, the skb mark field is set regardless
of the configured mode which cause a corruption of the mark field in case
of switchdev mode.

Fix by overriding the mark value back to 0 in the representor tc update
skb flow.

Fixes: 8f1e0b97 ("net/mlx5: E-Switch, Mark miss packets with new chain id mapping")
Signed-off-by: Maor Dickman <maord@nvidia.com>
Reviewed-by: Raed Salem <raeds@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en/rep/tc.c

@@ -626,6 +626,11 @@ bool mlx5e_rep_tc_update_skb(struct mlx5_cqe64 *cqe,
 	if (!reg_c0)
 		return true;
 
+	/* If reg_c0 is not equal to the default flow tag then skb->mark
+	 * is not supported and must be reset back to 0.
+	 */
+	skb->mark = 0;
+
 	priv = netdev_priv(skb->dev);
 	esw = priv->mdev->priv.eswitch;