net/mlx5e: Create auxdev devlink instance in the same ns as parent devlink

Commit cited in "fixes" tag moved the devlink port under separate
devlink entity created for auxiliary device. Respect the network
namespace of parent devlink entity and allocate the devlink there.

Fixes: ee75f1fc ("net/mlx5e: Create separate devlink instance for ethernet auxiliary device")
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>