ASoC: pcm3168a: refactor hw_params routine

ASoC: pcm3168a: refactor hw_params routine

- group together code lines that calculate value for msad/msda field

- rename variables to better match their meaning:
    val -> ms,
    max_ratio -> num_scki_ratios

- update variable types to match exactly parameters or return types
  of the calls where those variables are used

- write two fields of the same register in a single regmap call

Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Link: https://lore.kernel.org/r/20220208084220.1289836-3-nikita.yoush@cogentembedded.com
Signed-off-by: Mark Brown <broonie@kernel.org>