soc/intel_adsp: Low level HDA driver and tests

Adds a header only low level driver for HDA streams along with smoke
tests to ensure basic host in and out stream functionality.

The tests require host side interaction. In cavstool a new HDAStream
class encapsulates somewhat a single stream and its registers. This
is manipulated in the tests using IPC with the Host ensuring that a
specific order of operations is done.

This low level driver allows testing certain hardware configurations
and flows with easy to use register dump debugging. It is not
intended to be the end API an application might use. That would be
a DMA driver using this.

Signed-off-by: Tom Burdick <thomas.burdick@intel.com>