ASoC: uda134x: Remove is_powered_on_standby from platform data

According to its documentation the is_powered_on_standby field of the
uda134x platform data is supposed to prevent the the driver from shutting
down the ADC and DAC in standby mode. This behavior was broken in commit
commit f0fba2ad

 ("ASoC: multi-component - ASoC Multi-Component Support")
almost 5 years ago and all the flag does now is cause the driver to go to
SND_SOC_BIAS_ON in probe, just for the ASoC core to put it back into
SND_SOC_BIAS_STANDBY right after probe.

Apparently the intended behavior has not been missed, so just remove
is_powered_on_standby from the platform data struct.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>