soundwire: intel: handle disabled links

On most hardware platforms, SoundWire interfaces are pin-muxed with
other interfaces (typically DMIC or I2S) and the status of each link
needs to be checked at boot time.

For Intel platforms, the BIOS provides a menu to enable/disable the
links separately, and the information is provided to the OS with an
Intel-specific _DSD property. The same capability will be added to
revisions of the MIPI DisCo specification.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20190821185821.12690-5-pierre-louis.bossart@linux.intel.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>