soundwire: stream: special-case the bus compute_params() routine

For BPT support, we want to allocate the entire audio payload and
bypass the allocation based on PCM/PDM parameters.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Liam Girdwood <liam.r.girdwood@intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Tested-by:  <shumingf@realtek.com>
Link: https://lore.kernel.org/r/20250227140615.8147-6-yung-chuan.liao@linux.intel.com


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