Fix model

Thank you for the fix https://github.com/stripe/aws-go/commit/6bceebd6140ba9652b97ca2261eadd3af769d837.

Unfortunately, some query tag in SQS are not created correctly. For example:

Expected:

```go
 type SendMessageBatchRequest struct {
	Entries  []SendMessageBatchRequestEntry `query:"SendMessageBatchRequestEntry" xml:"SendMessageBatchRequestEntry"`
	QueueURL aws.StringValue                `query:"QueueUrl" xml:"QueueUrl"`
 }
```

Actual:

```go
 type SendMessageBatchRequest struct {
	Entries  []SendMessageBatchRequestEntry `query:"Entries" xml:"SendMessageBatchRequestEntry"`
	QueueURL aws.StringValue                `query:"QueueUrl" xml:"QueueUrl"`
 }
```

I try to fix this but I'm not sure this is a right fix.