soundwire: cadence: allocate/free dma_data in set_sdw_stream

The current memory allocation is somewhat strange: the dma_data is
allocated in set_sdw_stream, but released in the intel DAI
shutdown. This no longer works with the multi-cpu implementation,
since the dma_data is released in the dai shutdown which takes place
before the dailink shutdown.

Move to a more symmetric allocation where the dma_data is allocated
with non-NULL SoundWire stream, and conversely released when a NULL
stream is provided - for consistency with the stream startup and
shutdown operations.

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/20200630184356.24939-5-yung-chuan.liao@linux.intel.com


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