Fix accuracy validation logic for MPS (#156385)
Summary:
As it does not support full fp64, validate against float32
X-link: https://github.com/pytorch/pytorch/pull/156385
Approved by: https://github.com/Skylion007
Reviewed By: atalman
Differential Revision: D76973534
fbshipit-source-id: 757eabb835f568c3b311431ba469ad977533b581
