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().

cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
cc: Liam Girdwood <lrg@ti.com>
cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
cc: Jaroslav Kysela <perex@perex.cz>
cc: Takashi Iwai <tiwai@suse.de>
cc: alsa-devel@alsa-project.org
Acked-by: Jarkko Nikula <jarkko.nikula@bitmer.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>