ASoC: bcm2835-i2s: Use maple tree register cache

ASoC: bcm2835-i2s: Use maple tree register cache

The bcm2835 I2S driver uses a rbtree register cache but has no clear need
to do so. Since the maple tree cache uses a more modern data structure and
makes implementation decisions more suitable for current systems switch the
driver to use that instead. No functional changes.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://patch.msgid.link/20240924-asoc-bcm-maple-v1-1-9d221f4a0195@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>