[llvm] [SelectionDAG][RISCV] Avoid store merging across function calls (PR #130430)

[Luke Lau via llvm-commits]

https://github.com/lukel97 approved this pull request.

LGTM to me too. It would be nice to update hasCallInLdStChain to only check the first load/store pair but that's an optimisation, feel free to leave it to another PR if you want

https://github.com/llvm/llvm-project/pull/130430