{rdma,net}/mlx5: export mlx5_vport_get_vhca_id

vhca id is already cached in the vport structure no need to query on
every mlx5 layer, use the mlx5_vport_get_vhca_id, where possible.

Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Alexei Lazar <alazar@nvidia.com>
Reviewed-by: Feng Liu <feliu@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>