ASoC: dapm: Add support for hw_free on CODEC to CODEC links

Currently, on power down for a CODEC to CODEC DAI link we only call
digital_mute and shutdown. Provide a little more flexibility for drivers
by adding a call to hw_free as well.

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