devlink: introduce __devlink_alloc() with dev driver pointer

devlink: introduce __devlink_alloc() with dev driver pointer

Introduce __devlink_alloc() as an internal devlink allocator that
accepts a struct device_driver pointer and stores it in the devlink
instance. This allows internal devlink code (e.g. shared instances)
to associate a driver with a devlink instance without need to pass dev
pointer.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Link: https://patch.msgid.link/20260312100407.551173-8-jiri@resnulli.us
Signed-off-by: Jakub Kicinski <kuba@kernel.org>