net: devlink: let the core report the driver name instead of the drivers

The driver name is available in device_driver::name. Right now,
drivers still have to report this piece of information themselves in
their devlink_ops::info_get callback function.

In order to factorize code, make devlink_nl_info_fill() add the driver
name attribute.

Now that the core sets the driver name attribute, drivers are not
supposed to call devlink_info_driver_name_put() anymore. Remove
devlink_info_driver_name_put() and clean-up all the drivers using this
function in their callback.

Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Tested-by: Ido Schimmel <idosch@nvidia.com> # mlxsw
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>