[clang] [llvm] [MIPS] Add MIPS i6400 and i6500 processors (PR #130587)

[Mallikarjuna Gouda via llvm-commits]

mgoudar wrote:

> Lets wait another day or two, since someone may have additional comments. Thanks @mgoudar!

sure. thank you.

https://github.com/llvm/llvm-project/pull/130587