ASoC: tlv320aic32x4: Break out clock setting into separate function

Break the clock setting logic out from the main hw_params.  It's
rather large and unweildy and makes for a large function.  This
also better enables some of the following changes to the clock
tree access in the driver.

Signed-off-by: Annaliese McDermond <nh6z@nh6z.net>
Signed-off-by: Mark Brown <broonie@kernel.org>