[llvm] [DAG]SimplifyDemandedVectorElts-add ISD::AVGCEILS/AVGCEILU/AVGFLOORS/AVGFLOORU nodes (PR #86284)

[via llvm-commits]

aniplcc wrote:

Also, the ISD:: opcode passed to SimplifyDemandedVectorElts is `INTRINSIC_WO_CHAIN`(45) rather than one of AVGCEIL(S/U)/AVGFLOOR(S/U)?

https://github.com/llvm/llvm-project/pull/86284