ASoC: arizona: Add handling for audio related device tree entries

Currently all the audio related device tree entries are handled by the
MFD code, for most parts of the Arizona driver we group the device
tree handling with the component that uses it and should do so here as
well.

Add handling in the ASoC code for the audio device tree entries, a
later patch removes the MFD side handling but there is no harm in it
being duplicated temporarily.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Mark Brown <broonie@kernel.org>