fix multinomial kernels to properly advance random states (#38046)
Summary:
Before, multinomial kernels did not advance random states enough, which lead to the same sequence being generated over and over with a shift of 4. This PR fixes that.
Fixes https://github.com/pytorch/pytorch/issues/37403
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38046
Differential Revision: D21516542
Pulled By: ngimel
fbshipit-source-id: 23248a8c3a5c44316c4c35cd71a8c3b5f76c90f2
