soundwire: cadence: multi-link support

Enable multi-link (aka multi-master configuration). In this
configuration, updates and commands with the 'ssp_sync' tag will be
deferred and controlled by the gsync hardware signal.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200317163329.25501-17-pierre-louis.bossart@linux.intel.com


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