ASoC: Remove obsolete OMAP3 machine drivers

The new omap-twl4030 handles the boards used the following drivers:
igep0020, omap3beagle, omap3evm and overo.
Remove these drivers since they are mostly identical and we already have
drop in replacement for all of them.

Note: Earlier patch added the needed code for the board files to retain the
audio support for boards I can identify that used one of the removed
drivers.
If I missed something please take a look at for example:
arch/arm/mach-omap2/board-omap3beagle.c on how add support for omap-twl4030
audio.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>