ASoC: omap-pcm: Fix the no period wakeup implementation

After omap_request_dma the BLOCK_IRQ is enabled as default
configuration for the channel.
If we are requested for no period wakeup, we need to disable
the BLOCK_IRQ in order to not receive any interrupts.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>