[llvm] [ARM] Add combine for vector_deinterleave load (PR #225747)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

Can you add more tests for different sizes? vld2 doesn't seem to be generated at the moment. We don't seem to have a lot of arm neon vldn tests.

We will need to add MVE lowering too - there should be more existing tests for those in the Thumb2/mve-*.ll tests.

https://github.com/llvm/llvm-project/pull/225747