ASoC: tlv320aic31xx: Fix 24bit samples with I2S format and 12MHz mclk

I2S format requires bitclock to have an exact amount of cycles in a
frame for audio to work cleanly. With dsp formats that is not so
important.

Updates aic31xx_setup_pll() to look for a line in aic31xx_divs table
that produces the best match for the bitclock and adds lines to
aic31xx_divs for 12MHz mclk and 24bit samples.

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>