ASoC: rt5670: add rt5672 codec support

rt5672 is very similar to rt5670. Therefore we use one codec driver
to support both codecs. The difference between rt5670 and rt5672 is
there is some difference in their dapm routing table.

Signed-off-by: Bard Liao <bardliao@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>