fix batch_isend_irecv example incorrect usage (#110408)
mismatched dtypes silently leads to wrong outputs in nccl
```
1:recv_tensor=tensor([0., 0.], device='cuda:1')
0:recv_tensor=tensor([2.8026e-45, 0.0000e+00], device='cuda:0')
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110408
Approved by: https://github.com/awgu, https://github.com/Neilblaze
