add a helper function to get the hw device_t from an audio_softc
Add common audio converters for software volume control. Only supports
slinear16_le and slinear16_be for now.

Convert pad(4) to use the new converters.
add software volume controls
padvol.c is no more
welcome to 2014j
awinir(4): Add support for Allwinner A20/A31 IR receiver.
mention tzcode 2014j