ASoC: max98088: Add TLV data for volume controls.

Specify volumes as defined in the MAX98088/9 data sheet.  Allows ALSA
lib snd_mixer_selem_get_playback_dB_range and related functions to
work.

Signed-off-by: Dylan Reid <dgreid@chromium.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>