* SOUND_x enum can be generated by audiohw_settings.h along with settings
entries and sound_val2phys.
* VOLUME_MIN and VOLUME_MAX are no longer necessary within sound.c. If
you need them, they are for target-defined purposes.
* Fix up SDL volume implementation in sdl.c. Move sim volume calculation
code to pcm-sdl.c.
* Min trigger tresholds were based upon VOLUME_MIN for some reason.
These setting have nothing to do with playback volume. Since it is no
longer present, set these at -89dB which is the minimum peak meter
sensitivity setting.
* Fix an oversight in wm8758.c. I forgot to add the dB->register
conversion to audiohw_set_volume.
Change-Id: Ie1df33f1793eee75e6793f16bc7bddd16edb7f75