If multiple serializers are connected in the system and the number of
channels will need to use more than one serializer the mask to enable the
serializers were left to 0 if tdm_mask is provided

Fixes: dd55ff83 ("ASoC: davinci-mcasp: Add set_tdm_slots() support")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>