net/mlx5: Base ECVF devlink port attrs from 0

net/mlx5: Base ECVF devlink port attrs from 0

Adjust the vport number by the base ECVF vport number so the port
attributes start at 0. Previously the port attributes would start 1
after the maximum number of host VFs.

Fixes: dc13180824b7 ("net/mlx5: Enable devlink port for embedded cpu VF vports")
Signed-off-by: Daniel Jurgens <danielj@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Link: https://patch.msgid.link/20250820133209.389065-2-mbloch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>