ASoC: codecs/jz4770: Reset interrupt flags in bias PREPARE

In case a poll for RUP times out, we might be left with some IRQ flags
that should be cleared before the next power on.

Signed-off-by: Christophe Branchereau <cbranchereau@gmail.com>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20201207125338.119397-2-paul@crapouillou.net
Signed-off-by: Mark Brown <broonie@kernel.org>