ASoC: SOF: Correct sps->stream and cstream nullity

Merge series from Peter Ujfalusi <peter.ujfalusi@linux.intel.com>:

The Nullity of sps->cstream needs to be checked in sof_ipc_msg_data() and not
assume that it is not NULL.
The sps->stream must be cleared to NULL on close since this is used as a check
to see if we have active PCM stream.

sound/soc/sof/pcm.c

@@ -511,6 +511,8 @@ static int sof_pcm_close(struct snd_soc_component *component,
 		 */
 	}
 
+	spcm->stream[substream->stream].substream = NULL;
+
 	return 0;
 }
 

sound/soc/sof/stream-ipc.c

@@ -43,14 +43,18 @@ int sof_ipc_msg_data(struct snd_sof_dev *sdev,
 				return -ESTRPIPE;
 
 			posn_offset = stream->posn_offset;
-		} else {
+		} else if (sps->cstream) {
 
 			struct sof_compr_stream *sstream = sps->cstream->runtime->private_data;
 
 			if (!sstream)
 				return -ESTRPIPE;
 
 			posn_offset = sstream->posn_offset;
+
+		} else {
+			dev_err(sdev->dev, "%s: No stream opened\n", __func__);
+			return -EINVAL;
 		}
 
 		snd_sof_dsp_mailbox_read(sdev, posn_offset, p, sz);