ASoC: tlv320aic31xx: Reformat header file using GENMASK and BIT macros

We also move the comments describing the registers to after the register
definition to remove non-uniform vertical white-space, this makes
cross-referencing with the datasheet much easier.
Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>