ASoC: SOF: topology: simplify code to prevent static analysis warnings

make KCFLAGS='-fanalyzer' sound/soc/sof/intel/ reports a possible NULL
pointer dereference.

sound/soc/sof/topology.c:1136:21: error: dereference of NULL ‘w’
[CWE-476] [-Werror=analyzer-null-dereference]

 1136 |     strcmp(w->sname, rtd->dai_link->stream_name))

The code is rather confusing and can be simplified to make static
analysis happy. No functionality change.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Yaochun Hung <yc.hung@mediatek.com>
Link: https://lore.kernel.org/r/20230731213748.440285-4-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/topology.c

@@ -1117,10 +1117,11 @@ static void sof_disconnect_dai_widget(struct snd_soc_component *scomp,
 {
 	struct snd_soc_card *card = scomp->card;
 	struct snd_soc_pcm_runtime *rtd;
+	const char *sname = w->sname;
 	struct snd_soc_dai *cpu_dai;
 	int i, stream;
 
-	if (!w->sname)
+	if (!sname)
 		return;
 
 	if (w->id == snd_soc_dapm_dai_out)
@@ -1133,7 +1134,7 @@ static void sof_disconnect_dai_widget(struct snd_soc_component *scomp,
 	list_for_each_entry(rtd, &card->rtd_list, list) {
 		/* does stream match DAI link ? */
 		if (!rtd->dai_link->stream_name ||
-		    strcmp(w->sname, rtd->dai_link->stream_name))
+		    strcmp(sname, rtd->dai_link->stream_name))
 			continue;
 
 		for_each_rtd_cpu_dais(rtd, i, cpu_dai)