ASoC: omap-pcm: Convert to use dmaengine

Original author: Russell King <rmk+kernel@arm.linux.org.uk>

Switch the omap-pcm to use dmaengine.
Certain features are not supported by after dmaengine conversion:
1. No period wakeup mode
   DMA engine has no way to communicate this information through
   standard channels.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>