soundwire: intel: add sdw_stream_setup helper for .startup callback

The sdw stream is allocated and stored in dai to share the sdw runtime
information.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Rander Wang <rander.wang@linux.intel.com>
Acked-by: Sanyog Kale <sanyog.r.kale@intel.com>
Link: https://lore.kernel.org/r/20200215014740.27580-5-pierre-louis.bossart@linux.intel.com


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