ASoC: OMAP: Build config cleanup for McBSP

The McBSP driver stack has been moved, and rewritten resulting a single
driver - selected by CONFIG_SND_OMAP_SOC_MCBSP. There is no longer need to
have CONFIG_OMAP_MCBSP anymore.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Mark Brown <broonoie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@ti.com>