[llvm] [Mips] Fix atomic min/max generate mips4 instructions when compiling for mips2 (PR #149983)

[via llvm-commits]

yingopq wrote:

Thanks, I would see this error.
I tested this issue using `sudo ./build/bin/clang --target=mipsel-unknown-linux-gnu -march=mips2 -emit-llvm -S 1.c` and `sudo ./build/bin/clang --target=mipsel-unknown-linux-gnu -fuse-ld=/usr/bin/mipsel-linux-gnu-ld 1.ll -o a1main`, so I did not find this error.

https://github.com/llvm/llvm-project/pull/149983