ASoC: OMAP: mcbsp fixes for enabling ARM multiplatform support

We cannot include any plat or mach headers for the multiplatform
support.

Fix the issue by defining local mcbsp_omap1().

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