soc-pcm: WARN_ON invalid playback route

Signed-off-by: Iliyan Malchev <malchev@google.com>
diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 65cee5d..8614a92 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -25,6 +25,7 @@
 #include <linux/debugfs.h>
 #include <linux/dma-mapping.h>
 #include <linux/export.h>
+#include <linux/bug.h>
 #include <sound/core.h>
 #include <sound/pcm.h>
 #include <sound/pcm_params.h>
@@ -2026,6 +2027,7 @@
 		if (paths < 0) {
 			dev_warn(fe->dev, "%s no valid %s route from source to sink\n",
 					fe->dai_link->name,  "playback");
+			WARN_ON(1);
 			ret = paths;
 			goto out;
 		}