ASoC: ak4642: Revive ak4642_snd_controls

This patch revive ak4642_snd_controls which was removed on
f0fba2ad

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>