ASoC: rt5677: keep analog power register at SND_SOC_BIAS_OFF

ASoC: rt5677: keep analog power register at SND_SOC_BIAS_OFF

Instead of clearing RT5677_PWR_ANLG2 (MX-64h) to 0 at SND_SOC_BIAS_OFF,
we only clear the RT5677_PWR_CORE bit which is set at SND_SOC_BIAS_PREPARE.
MICBIAS control bits are left unchanged.

This fixed the bug where if MICBIAS1 widget is forced on, MICBIAS
control bits will be cleared at suspend and never turned back on again,
since DAPM thinks the widget is always on.

Signed-off-by: Ben Zhang <benzh@chromium.org>
Signed-off-by: Curtis Malainey <cujomalainey@chromium.org>
Link: https://lore.kernel.org/r/20190906194636.217881-3-cujomalainey@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>