ASoC: SOF: sof-audio: skip prepare/unprepare if swidget is NULL

ASoC: SOF: sof-audio: skip prepare/unprepare if swidget is NULL

commit 0ad84b11f2f8dd19d62d0b2ffd95ece897e6c3dc upstream.

Skip preparing/unpreparing widgets if the swidget pointer is NULL. This
will be true in the case of virtual widgets in topology that were added
for reusing the legacy HDA machine driver with SOF.

Fixes: 9862dcf70245 ("ASoC: SOF: don't unprepare widget used other pipelines")
Cc: <stable@vger.kernel.org> # 6.1
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20230118101255.29139-3-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>