ASoC: dapm: Fix compilation warning

Fix following:
sound/soc/soc-dapm.c: In function ‘dapm_clock_event’:
sound/soc/soc-dapm.c:1021:1: warning: control reaches end of non-void function [-Wreturn-type]
Signed-off-by: NMarek Belisko <marek.belisko@open-nandra.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/soc-dapm.c

@@ -1019,6 +1019,7 @@ int dapm_clock_event(struct snd_soc_dapm_widget *w,
 		return 0;
 	}
 #endif
+	return 0;
 }
 EXPORT_SYMBOL_GPL(dapm_clock_event);