ASoC: codecs: Make OF supported CODECs visible in Kconfig

Now that we have a generic card driver we can't rely on the card driver
selecting the CODECs for us so make the CODECs that can be enabled with
OF directly selectable in Kconfig. For the platforms not using OF it's
not clear that we don't still want to have some board specific selection
since the kernel needs to contain code to register the devices; ACPI could
provide this from firmware does not yet support any kind of generic card.

It may also be desirable to hide these if OF is not enabled to reduce
noise.

Signed-off-by: Mark Brown <broonie@linaro.org>