soundwire: add flag to ignore all command/control for mockup devices

soundwire: add flag to ignore all command/control for mockup devices

SoundWire mockup devices don't take part in the command/control
protocol, so all commands will complete with -ENODATA or
Command_Ignored results. With a flag, we can suppress such errors in
the bus management and make it appear as if all read/writes succeed.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20210714032209.11284-7-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>