ASoC: es8316: fix headphone mixer volume table

ASoC: es8316: fix headphone mixer volume table

This patch fix setting table of Headphone mixer volume.
Current code uses 4 ... 7 values but these values are prohibited.

Correct settings are the following:
  0000 -12dB
  0001 -10.5dB
  0010 -9dB
  0011 -7.5dB
  0100 -6dB
  1000 -4.5dB
  1001 -3dB
  1010 -1.5dB
  1011 0dB

Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Reviewed-by: Daniel Drake <drake@endlessm.com>
Link: https://lore.kernel.org/r/20190826153900.25969-1-katsuhiro@katsuster.net
Signed-off-by: Mark Brown <broonie@kernel.org>