apt_key: Fix traceback when key_id format is invalid

fail_json() take a mandatory msg parameter:

```
% ansible all -m apt_key -a 'id=invalid'
docker0 | FAILED >> {
    "failed": true, 
    "msg": "Traceback (most recent call last):\n  File \"<stdin>\", line 1588, in <module>\n  File \"<stdin>\", line 202, in main\nTypeError: fail_json() takes exactly 1 argument (2 given)\n", 
    "parsed": false
}
```

And with this fix:

```
% ansible all -m apt_key -a 'id=invalid'
docker0 | FAILED >> {
    "failed": true, 
    "id": "invalid", 
    "msg": "Invalid key_id"
}
```