ASoC: tlv320adcx140: Add decimation filter support

Add decimation filter selection support.
Per Section 8.3.6.7 the Digital Decimation Filter is selectable between
a Linear Phase, Low Latency, and Ultra Low Latency filer.

Signed-off-by: Dan Murphy <dmurphy@ti.com>
Link: https://lore.kernel.org/r/20200221181358.22526-2-dmurphy@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>