Once we've set-up the HDA stream and its format, we currently don't
support additional format changes. We already have a protection in the
.prepare case, but this needs to be added in the hw_params too.

In mixing use cases where two DPCM FEs are connected to the same BE,
if can happen that there are multiple calls to the BE hw_params when
the two FEs are configured simultaneously.

This could alternatively be fixed at the DPCM level but that's a more
intrusive change requiring infrastructure changes: this would need to
be paired with the definition of fixed hw_params at the mixer level.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20220421203201.1550328-15-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>