ASoC: (cosmetic) simplify dpcm_prune_paths()

Currently dpcm_prune_paths() has up to 4 nested condition and loop
levels, which forces the code to use flags for flow control.
Extracting widget status verification code from dpcm_prune_paths()
into a separate function simplifies the code.
Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Link: https://lore.kernel.org/r/20200312095214.15126-2-guennadi.liakhovetski@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-pcm.c

@@ -1626,22 +1626,14 @@ void dpcm_path_put(struct snd_soc_dapm_widget_list **list)
 	snd_soc_dapm_dai_free_widgets(list);
 }
 
-static int dpcm_prune_paths(struct snd_soc_pcm_runtime *fe, int stream,
-	struct snd_soc_dapm_widget_list **list_)
+static bool dpcm_be_is_active(struct snd_soc_dpcm *dpcm, int stream,
+			      struct snd_soc_dapm_widget_list *list)
 {
-	struct snd_soc_dpcm *dpcm;
-	struct snd_soc_dapm_widget_list *list = *list_;
 	struct snd_soc_dapm_widget *widget;
 	struct snd_soc_dai *dai;
-	int prune = 0;
-	int do_prune;
-
-	/* Destroy any old FE <--> BE connections */
-	for_each_dpcm_be(fe, stream, dpcm) {
 	unsigned int i;
 
 	/* is there a valid CPU DAI widget for this BE */
-		do_prune = 1;
 	for_each_rtd_cpu_dais(dpcm->be, i, dai) {
 		widget = snd_soc_dai_get_widget(dai, stream);
 
@@ -1650,21 +1642,30 @@ static int dpcm_prune_paths(struct snd_soc_pcm_runtime *fe, int stream,
 		 * widgets are in the active list.
 		 */
 		if (widget && widget_in_list(list, widget))
-				do_prune = 0;
+			return true;
 	}
-		if (!do_prune)
-			continue;
 
 	/* is there a valid CODEC DAI widget for this BE */
-		do_prune = 1;
 	for_each_rtd_codec_dais(dpcm->be, i, dai) {
 		widget = snd_soc_dai_get_widget(dai, stream);
 
 		/* prune the BE if it's no longer in our active list */
 		if (widget && widget_in_list(list, widget))
-				do_prune = 0;
+			return true;
 	}
-		if (!do_prune)
+
+	return false;
+}
+
+static int dpcm_prune_paths(struct snd_soc_pcm_runtime *fe, int stream,
+			    struct snd_soc_dapm_widget_list **list_)
+{
+	struct snd_soc_dpcm *dpcm;
+	int prune = 0;
+
+	/* Destroy any old FE <--> BE connections */
+	for_each_dpcm_be(fe, stream, dpcm) {
+		if (dpcm_be_is_active(dpcm, stream, *list_))
 			continue;
 
 		dev_dbg(fe->dev, "ASoC: pruning %s BE %s for %s\n",