ARM: OMAP: Remove unused platform devices for old ALSA code

This patch removes old platform devices. The should be now
replaced with ASoC driver. For boards not yet using ASoC,
please see sound/soc/omap/osk5912.c.

This patch is based on an earlier patch by Arun KS.

Signed-off-by: Arun KS <arunks@mistralsolutions.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>