net/mlx5: Allow mlx5_esw_offloads_devlink_port_register() to register SFs

Currently there is a separate set of functions used to
register/unregister the SF. The only difference is currently the ops
struct. Move the struct up and use it for SFs in
mlx5_esw_offloads_devlink_port_register().

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Shay Drory <shayd@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>