ASoC: tlv312aic23: unbreak resume

ASoC: tlv312aic23: unbreak resume

commit e875c1e3e758447ba81ca450d89434b3b0496d37 upstream.

* commit f9dfbf9 "ASoC: tlv320aic23: convert to soc-cache" leads to
a bug preventing resumeof the codec as regmap expects a 9 bits data
register but 0xFFFF is passed in tlv320aic23_set_bias_level and this
values gets cached preventing any write to the TLV320AIC23_PWR
register as the final value produced by regmap is (register << 9) | value

* this patch solves the problem by only working on the 9 bits the
register contains.

Signed-off-by: Eric Bénard <eric@eukrea.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>