devlink: include the generated netlink header

Put the newly added generated header to the include list. Remove the
duplicated temporary function prototypes.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230803111340.1074067-12-jiri@resnulli.us


Signed-off-by: Jakub Kicinski <kuba@kernel.org>