[llvm] [WIP][SDAG] Add partial_reduce_sumla node (PR #141267)

[Philip Reames via llvm-commits]

preames wrote:

I've posted https://github.com/llvm/llvm-project/pull/141970 which will split the legalize table by opcode.  Once this lands, I'll rebase.  My plan is to leave the AArch64 cases in the default (non-legal) state, and focus only on the RISCV support.  AArch64 folks can follow up with the USDOT support if desired.  

https://github.com/llvm/llvm-project/pull/141267