fixes return data structure (#22830)

The return was being re-written instead of updated so warnings were
lost.  This patch now updates the result instead of replacing it.
(cherry picked from commit d6787632c9)

lib/ansible/modules/network/ios/ios_command.py

@@ -218,11 +218,11 @@ def main():
         module.fail_json(msg=msg, failed_conditions=failed_conditions)
 
 
-    result = {
+    result.update({
         'changed': False,
         'stdout': responses,
         'stdout_lines': list(to_lines(responses))
-    }
+    })
 
     module.exit_json(**result)