soundwire: intel: add multi-link support

soundwire: intel: add multi-link support

The multi-link support is enabled with a hardware gsync signal
connecting all links. All commands and operations which typically are
handled on an SSP boundary will be deferred further and enabled across
all links with the 'syncGo' sequence.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20200901150556.19432-4-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>