net: devlink: fix unlocked vs locked functions descriptions

To be unified with the rest of the code, the unlocked version (devl_*)
of function should have the same description in documentation as the
locked one. Add the missing documentation. Also, add "Context"
annotation for the locked versions where it is missing.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>