[AArch64] -mcpu=native CPU detection for Cavium processors

This small patch updates the CPU detection for Cavium processors when
-mcpu=native is passed on compile-line.

Patch by Stefan Teleman
Differential Revision: https://reviews.llvm.org/D51939


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@343897 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed