ASoC: tlv320dac33: Avoid multiple soft power up

During playback start the codec has been already powered at
BIAS_ON event time, so there's no need to enable the codec again.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>