soundwire: intel: filter SoundWire controller device search

The convention is that the SoundWire controller device is a child of
the HDAudio controller. However there can be more than one child
exposed in the DSDT table, and the current namespace walk returns the
last (incorrect) device.

Intel documentation states that bits 28..31 of the _ADR field
represent the link type, with SoundWire assigned the value 4.

Add a filter and terminate early when a valid _ADR is provided,
otherwise keep iterating to find the next child.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>