soundwire: enable Data Port test modes

soundwire: enable Data Port test modes

Test modes are required for all SoundWire IP, and help debug
integration issues. In theory each port can be configured with a
different mode but to simplify this patch only offers separate
configurations for the Master and Slave ports - this covers 99% of the
intended cases during platform integration.

The test mode value is set via platform-specific ways.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20200920193207.31241-2-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>