OMAP: McBSP: Add 32-bit mode support

This patchs should allow to use 32-bit samples on e.g. TLV320AIC3x codec,
or others.

Signed-off-by: Sergey Lapin <slapin@ossfans.org>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>