For some reason, the DAC/ADCs are not being powered up when I try and
use the UDA1341 driver; this used to work.  Looking back in the git
history, I don't see anything obvious which would cause this
regression.

However, from dumping the register writes, it seems that the codec is
powered down, and nothing calls set_bias_level to wake the codec up.

Moreover, this driver hasn't had DAPM support added to it, which
prevents platform drivers from taking advantage of DAPMs facilities.
So, let's add DAPM support to the driver.

As we move the power control for the DAC/ADC into DAPM, we no longer
need it in set_bias_level() - this function just becomes a way to
manipulate the power control and sync the register cache with the
hardware at the appropriate point.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Mark Brown <broonie@linaro.org>