[nnc] Fix dtype promotion involving scalars (#64002)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64002
Fixes https://github.com/pytorch/vision/issues/4315
Test Plan: Imported from OSS
Reviewed By: navahgar
Differential Revision: D30566979
Pulled By: bertmaher
fbshipit-source-id: eaa98b9534a926be7fcd337d46c5a0acb3243179
