[llvm] [PowerPC] Remove chenzheng1030 as maintainer (PR #145519)

[Nikita Popov via llvm-commits]

nikic wrote:

Okay, I went ahead and merged this for now.

It would be great to find new maintainers though, would any of the people pinged above be interested?

https://github.com/llvm/llvm-project/pull/145519