ASoC: Fix build of OMAP sound drivers

There are build errors when building for some of the omap2/3 boards without
enabling sound:

sound/built-in.o:(.data+0x43bc): undefined reference to `soc_codec_dev_tlv320aic23'
sound/built-in.o:(.data+0x43cc): undefined reference to `tlv320aic23_dai'

Confused me quite a bit since the drivers that had references to the
codec weren't enabled. Turns out the Makefile was using the wrong
config option to enable them. Patch below.

Reported-by: Anand Gadiyar <gadiyar@ti.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>