[llvm] [AArch64][GlobalISel] Add patterns for scalar sqdmlal/sqdmlsl (PR #187246)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

We might need a pattern for a straight llvm.aarch64.neon.sqdmulls.scalar. There doesn't seem to be a lot of tests for them on their own at the moment. The index variant from #185836 maybe too.

https://github.com/llvm/llvm-project/pull/187246