OMAP: McBSP: Configure NO IDLE mode for DMA mode different of threshold

Use dma mode property to configure NO IDLE or SMART IDLE of McBSPs.

Signed-off-by: Eduardo Valentin <eduardo.valentin@nokia.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>