ASoC: don't set dapm->bias_level directly

Merge series from Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>:

We have many set_bias_level functions, thus dapm->bias_level should be
handled by owner function, not by its callback functions.

diff --cc sound/soc/codecs/rt700.c
Simple merge

diff --cc sound/soc/codecs/rt715.c
Simple merge