ASoC: tlv320adcx140: Fix mic gain registers

Fix the mic gain registers for channels 2-4.
The incorret register was being set as it was touching the CH1 config
registers.

Fixes: 37bde5acf040 ("ASoC: tlv320adcx140: Add the tlv320adcx140 codec driver family")
Signed-off-by: Dan Murphy <dmurphy@ti.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200427203608.7031-1-dmurphy@ti.com


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