ASoC: axi-i2s: let both capture and playback be optional

Both the capture and playback channels are optional in the axi_i2s IP
block. Reflect this in the driver by enabling only the channel(s) that
have a DMA.

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Mark Brown <broonie@kernel.org>
1 file changed