ASoC: Add SDCA IRQ support and some misc fixups

Merge series from Charles Keepax <ckeepax@opensource.cirrus.com>:

Add a maintainers entry for SDCA, do a couple of small fixups for
previous chains, and then adding the beginnings of the SDCA IRQ
handling. This is based around a regmap IRQ chip and a few helper
functions that can be called from the client drivers to setup the
IRQs.