ASoC: davinci-mcasp: Provide correct filter_data for dmaengine for non-DT boot

When we boot with non-DT mode the damengine will need the channel number and
a filter function in order to get the channel.
The filter_data is filled in the DAI driver while the filter_function will
be provided by the edma-pcm driver.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>