ASoC: Remove redundant regcache_sync call in cs42l73_resume

It's done in cs42l73_set_bias_level when the dapm.bias_level is switching
from SND_SOC_BIAS_OFF to SND_SOC_BIAS_STANDBY.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>