ASoC: cs42l43: Fix maximum ADC Volume

The range of ADC volume is -1 -> 3 (-6 to 18dB) so the number of levels
should actually be 4.

Fixes: fc918cbe ("ASoC: cs42l43: Add support for the cs42l43")
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20250306133254.1861046-1-ckeepax@opensource.cirrus.com


Signed-off-by: Mark Brown <broonie@kernel.org>