ASoC: ti: davinci-mcasp: Specify stream_name for playback/capture

In order to dai stream widgets to be created the stream_name must be set.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20200630125843.11561-2-peter.ujfalusi@ti.com


Signed-off-by: Mark Brown <broonie@kernel.org>