Request the DMA channel in the PCM open callback instead of the hwparams
callback, this allows us to let open fail if no dma channel is available. This
also fixes a bug where the channel will be requested multiple times if hwparams
is called multiple times.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>