net/mlx5: E-Switch, Pass metadata from FDB to eswitch manager

In order to do matching on metadata in slow path when demuxing traffic
to representors, explicitly enable the feature that allows HW to pass
metadata REG_C_0 from FDB to eswitch manager NIC_RX table.

Signed-off-by: Jianbo Liu <jianbol@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>