HD Audio device model in userspace for bhyve

The bhyve hypervisor does not have any sound card emulation at the moment. This project is proposed by Peter Grehan and aims to implement the High Definition Audio Specification which is one of the best performant and supported device in the nowadays operating systems. Some of the reasons to have this device are: support for multiple input and output streams, up to 16 channels per stream, command-response codec communication, DMA channel for each stream and it is interfaced with the PCI bus. The main goal is to have a functional implementation by the end of the summer that will allow playing sounds inside a bhyve virtual machine.