ASoC: Avoid direct register cache access when setting defaults

ASoC: Avoid direct register cache access when setting defaults

Directly accessing the register cache means that we can't use anything
except a flat register cache so use snd_soc_update_bits().

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>