ASoC: tlv320adcx140: add kcontrol for num biquads

ASoC: tlv320adcx140: add kcontrol for num biquads

The tlv320adcx140 chips have a configurable amount of biquad filters
enabled per input channel. Currently this number is always left at the
default value of 2 biquads per channel.
This commit adds a kcontrol to allow runtime configuration of the amount
of biquads per channel.

The configuration is controlled by bits [5-6] in the DSP_CFG1 register.

Signed-off-by: Emil-Juhl <juhl.emildahl@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://patch.msgid.link/20260113-sound-soc-codecs-tvl320adcx140-v4-9-8f7ecec525c8@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>