[x86] Fix Intel OpenCL builtin CalleeSavedRegs on skx

Summary: Align with AVX512 builtins implementations, some of which don't preserve rdi.

Reviewers: yubing, tianqing, craig.topper

Reviewed By: craig.topper

Subscribers: yaxunl, Anastasia, hiraditya

Differential Revision: https://reviews.llvm.org/D77032