vdpa/mlx5: Fix rule forwarding VLAN to TIR

Set the VLAN id to the header values field instead of overwriting the
headers criteria field.

Before this fix, VLAN filtering would not really work and tagged packets
would be forwarded unfiltered to the TIR.

Fixes: baf2ad3f ("vdpa/mlx5: Add RX MAC VLAN filter support")
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eli Cohen <elic@nvidia.com>
Message-Id: <20221114131759.57883-2-elic@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>