ASoC: SOF: ipc3-topology: Set scontrol->priv to NULL after freeing it

Since the scontrol->priv is freed up during load operation it should be set
to NULL to be safe against double freeing attempt.

Fixes: b5cee8feb1 ("ASoC: SOF: topology: Make control parsing IPC agnostic")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220331114757.32551-1-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/ipc3-topology.c

@@ -1592,6 +1592,7 @@ static int sof_ipc3_control_load_bytes(struct snd_sof_dev *sdev, struct snd_sof_
 	if (scontrol->priv_size > 0) {
 		memcpy(cdata->data, scontrol->priv, scontrol->priv_size);
 		kfree(scontrol->priv);
+		scontrol->priv = NULL;
 
 		if (cdata->data->magic != SOF_ABI_MAGIC) {
 			dev_err(sdev->dev, "Wrong ABI magic 0x%08x.\n", cdata->data->magic);