fix a bug in leakyReLU (#48265)
Summary:
The scale variable needs to be a scalar, otherwise it will report the following error: "RuntimeError: Cannot input a tensor of dimension other than 0 as a scalar argument"
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48265
Test Plan: Tested locally and the error disappeared.
Reviewed By: zhizhengwu
Differential Revision: D25105423
Pulled By: jerryzh168
fbshipit-source-id: 2a0df24cf7e40278a950bffe6e0a9552f99da1d1
