[tensorexpre] Add typecast when src and dest buf types are different in PlacementAllocate (#71934)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/71934
Test Plan: Imported from OSS
Reviewed By: ZolotukhinM
Differential Revision: D33826700
Pulled By: huiguoo
fbshipit-source-id: 9fb29a43ab5983586a6bfde3a34d7e2f2120ab0a
(cherry picked from commit 2bee018691ec888cb1ec761528951f5745d7ef79)
