ASoC: rt5682s: Downsizing the DAC volume scale

Use 0.75db/step of DAC volume instead of 1.5 to get
a more smooth volume curve.

Signed-off-by: Derek Fang <derek.fang@realtek.com>
Link: https://lore.kernel.org/r/20211021120303.4601-1-derek.fang@realtek.com


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