alsa: add Beagleboard SoC configuration.

This is exactly the same as the overo configuration. It might make sense
to have them in a single one.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
# CHANGED to not spew messages about beagle on non-beagle boards
Signed-off-by: Tony Lindgren <tony@atomide.com>