net/mlx5: fix vport index in port action

The rdma_core routine mlx5dv_dr_create_flow_action_dest_vport()
requires the vport id parameter to create port action.
The register c[0] value was used to deduce the port id value
and it fails in bonding configuration. The correct way is
to apply vport_num value queried from the rdma_core library.

Fixes: f07341e7aed3 ("net/mlx5: update source and destination vport translations")

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>