Adds lookup table for floating point decibel volume, and new functions
to allow for setting the decibel level on the DSP.
Signed-off-by: Connor McAdams <conmanx360@gmail.com>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>