ASoC: omap-pcm: Period wakeup disabling on OMAP2+

Allow disabling ALSA period wakeup interrupts.
This can only be done on OMAP2+ (2/3/4), since there
we can chain the DMA.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Jarkko Nikula <jhnikula@gmail.com>
Signed-off-by: Liam Girdwood <lrg@ti.com>