ASoC: cirrus: Use the maple tree register cache

Merge series from Mark Brown <broonie@kernel.org>:

The maple tree register register cache is now able to generate multi
register writes which was the last big feature of the rbtree cache that
it didn't support so let's update drivers to use the cache with the more
modern data structure.

diff --cc sound/soc/codecs/cs35l56-shared.c
Simple merge