Use the helper introduced by commit e135303b ("device: Add
dev_<level>_once variants") instead of open-coding the same operation.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200102133822.29346-4-geert+renesas@glider.beSigned-off-by: Mark Brown <broonie@kernel.org>