cnat: fix spinlock

Type: fix

Change-Id: Id6406702061ada54e51ebcf5c367328605de2b6b
Signed-off-by: Nathan Skrzypczak <nathan.skrzypczak@gmail.com>
diff --git a/src/plugins/cnat/cnat_src_policy.c b/src/plugins/cnat/cnat_src_policy.c
index e11e912..cac24b7 100644
--- a/src/plugins/cnat/cnat_src_policy.c
+++ b/src/plugins/cnat/cnat_src_policy.c
@@ -122,7 +122,10 @@
       if (PREDICT_FALSE (*port >= UINT16_MAX))
 	*port = clib_bitmap_next_clear (ca->bmap, MIN_SRC_PORT);
       if (PREDICT_FALSE (*port >= UINT16_MAX))
-	return -1;
+	{
+	  clib_spinlock_unlock (&ca->lock);
+	  return -1;
+	}
     }
   clib_bitmap_set_no_check (ca->bmap, *port, 1);
   *port = clib_host_to_net_u16 (*port);