ASoC: codecs: aw88261: add dvdd-supply property

Merge series from Bharadwaj Raju <bharadwaj.raju@machinesoul.in>:

The AW88261 has a DVDD chip which needs to be powered on for it to
function correctly. The property for this was missing, so this patchset
adds the dvdd-supply property which enables a regulator to be bound
to it in a device tree.