[llvm] [PowerPC] Adjust operand order of ADDItoc to be consistent with other ADDI* nodes (PR #93642)

[Kai Luo via llvm-commits]

bzEq wrote:

After remove the pattern, I don't think it's an NFC change now, since memoperands are removed from `ADDItoc` nodes now.

https://github.com/llvm/llvm-project/pull/93642