devlink: Add devlink_param for port register and unregister

Add functions to register and unregister for the driver supported
configuration parameters table per port.

v7->v8:
- Order the definitions following way as suggested by Jiri.
__devlink_params_register
__devlink_params_unregister
devlink_params_register
devlink_params_unregister
devlink_port_params_register
devlink_port_params_unregister
- Append with Acked-by: Jiri Pirko <jiri@mellanox.com&gt;.>

v2->v3:
- Add a helper __devlink_params_register() with common code used by
  both devlink_params_register() and devlink_port_params_register().

Cc: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Vasundhara Volam <vasundhara-v.volam@broadcom.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>