Replace driver's code with the generic helpers that do the same thing.
Remove todo entry.
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20171106191812.38927-6-noralf@tronnes.org