[X86] Don't accidentally enable PKU on cannon lake and icelake or CLWB on cannonlake.

We have cannonlake and icelake inheriting from skylake server in a switch using fallthroughs. But they aren't perfect supersets of skylake server.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@321504 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed