ASoC: cs4271: Add support for the external mclk

ASoC: cs4271: Add support for the external mclk

The mclk (master clock) of the cs4271 codec can be an input clock.

In this case the connected clock needs to be enabled outside of any
audio stream. Indeed, this clock is needed for i2c communication.

Add support of this clock and enable it before the first i2c transfer.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Link: https://patch.msgid.link/20251029093921.624088-5-herve.codina@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>