parallels: return earler in fail_format branch in parallels_open()

We do not need to perform any deallocation/cleanup if wrong format is
detected.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
diff --git a/block/parallels.c b/block/parallels.c
index ae006e7..12f38cf 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -1232,7 +1232,8 @@
 
 fail_format:
     error_setg(errp, "Image not in Parallels format");
-    ret = -EINVAL;
+    return -EINVAL;
+
 fail:
     /*
      * "s" object was allocated by g_malloc0 so we can safely