BoxWithNMSLimit support int `batch_splits` input (#47504)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47504
allow int type input of `batch_splits`
Test Plan:
```
buck test caffe2/caffe2/python/operator_test:torch_integration_test -- test_box_with_nms_limits
```
Reviewed By: jackm321
Differential Revision: D24629522
fbshipit-source-id: 61cb132e792bddd8f9f1bca5b808f1a9131808f0
