net/mlx5: DR, Fix matching on vport gvmi

Set vport gvmi in the tag, only when source gvmi is set in the bit mask.

Fixes: 26d688e3

 ("net/mlx5: DR, Add Steering entry (STE) utilities")
Signed-off-by: Hamdan Igbaria <hamdani@mellanox.com>
Reviewed-by: Alex Vesker <valex@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>