[llvm] [DAGCombiner] Fix crash in reassociationCanBreakAddressingModePattern for multi-memop nodes (PR #180268)

[Nicolai Hähnle via llvm-commits]

https://github.com/nhaehnle approved this pull request.

LGTM

(I think using auto-generated check lines would be best)

https://github.com/llvm/llvm-project/pull/180268