devlink: Move devlink dev info code to dev

Move devlink dev info callbacks, related drivers helpers functions and
other related code from leftover.c to dev.c. No functional change in
this patch.

Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>