[llvm] [PowerPC] Update maintainer (PR #145519)

[Nikita Popov via llvm-commits]

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

It looks like @chenzheng1030 hasn't been active in LLVM since September last year, so I'd like to check with PowerPC contributors whether we should update the [maintainer](https://llvm.org/docs/DeveloperPolicy.html#maintainers). Or even better, specify multiple maintainers, as is the case for most major targets nowadays.

cc @lei137 @amy-kwan @diggerlin @RolandF77 

>From 973ce1300b3a6bf64160c83a94beb928b3d3963e Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov at redhat.com>
Date: Tue, 24 Jun 2025 16:27:46 +0200
Subject: [PATCH] [PowerPC] Update maintainers

---
 llvm/Maintainers.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/llvm/Maintainers.md b/llvm/Maintainers.md
index 7bf722d5f18aa..cb2635c841d53 100644
--- a/llvm/Maintainers.md
+++ b/llvm/Maintainers.md
@@ -263,8 +263,7 @@ amaclean at nvidia.com (email), [AlexMaclean](https://github.com/AlexMaclean) (GitH
 
 #### PowerPC backend
 
-Zheng Chen \
-czhengsz at cn.ibm.com (email), [chenzheng1030](https://github.com/chenzheng1030) (GitHub)
+???
 
 #### RISCV backend
 
@@ -523,6 +522,7 @@ Kostya Serebryany ([kcc](https://github.com/kcc)) -- Sanitizers \
 Michael Spencer (bigcheesegs at gmail.com), [Bigcheese](https://github.com/Bigcheese)) -- Windows support in object tools \
 Alexei Starovoitov (alexei.starovoitov at gmail.com, [4ast](https://github.com/4ast)) -- BPF backend \
 Evgeniy Stepanov ([eugenis](https://github.com/eugenis)) -- Sanitizers
+Zheng Chen (czhengsz at cn.ibm.com, [chenzheng1030](https://github.com/chenzheng1030)) -- PowerPC backend
 
 ### Former maintainers of removed components