[llvm] [AMDGPU] Always lower s/udiv64 by constant to MUL (PR #100723)

[Matt Arsenault via llvm-commits]

================
@@ -6405,7 +6405,8 @@ SDValue TargetLowering::BuildSDIV(SDNode *N, SelectionDAG &DAG,
     if (VT.isVector())
       WideVT = EVT::getVectorVT(*DAG.getContext(), WideVT,
                                 VT.getVectorElementCount());
-    if (isOperationLegalOrCustom(ISD::MUL, WideVT)) {
+    if (isOperationLegalOrCustom(ISD::MUL, WideVT) ||
----------------
arsenm wrote:

I primarily want to not have any new TLI hook. Quantity of test changes doesn't mean it's worse, just update them? 

https://github.com/llvm/llvm-project/pull/100723