Fixed NameError on result_dir when calling with --image-only

Signed-off-by: Brian C. Lane <bcl@redhat.com>

src/sbin/livemedia-creator

@@ -1395,8 +1395,8 @@ def main():
             log.error("ERROR: Image creation failed: %s", e)
             sys.exit(1)
 
+    result_dir = None
     if not opts.image_only:
-        result_dir = None
         if opts.make_iso:
             work_dir = tempfile.mkdtemp(prefix="lmc-work-")
             log.info("working dir is %s", work_dir)