The devlink parameter of the devlink_nl_cmd_region_read_chunk_fill
function is not used. Remove it, to simplify the function signature.

Once removed, it is also obvious that the devlink parameter is not
necessary for the devlink_nl_region_read_snapshot_fill either.
Signed-off-by: NJacob Keller <jacob.e.keller@intel.com>
Acked-by: NJakub Kicinski <kuba@kernel.org>
Reviewed-by: NJiri Pirko <jiri@nvidia.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>