Revert "Add support for single reductions in ComplexDeinterleavingPass (#112875)"

This reverts commit b3eede5.

This has been breaking most AArch64 stage2 builds for 4+ hours,
reverting to get the bots back to green.

https://lab.llvm.org/buildbot/#/builders/41/builds/4172
https://lab.llvm.org/buildbot/#/builders/4/builds/4281
https://lab.llvm.org/buildbot/#/builders/199/builds/263
https://lab.llvm.org/buildbot/#/builders/198/builds/334
https://lab.llvm.org/buildbot/#/builders/143/builds/4276
https://lab.llvm.org/buildbot/#/builders/17/builds/4725

Author: fhahn

llvm/include/llvm/CodeGen/ComplexDeinterleavingPass.h

@@ -35,7 +35,6 @@ struct ComplexDeinterleavingPass
 enum class ComplexDeinterleavingOperation {
   CAdd,
   CMulPartial,
-  CDot,
   // The following 'operations' are used to represent internal states. Backends
   // are not expected to try and support these in any capacity.
   Deinterleave,
@@ -44,7 +43,6 @@ enum class ComplexDeinterleavingOperation {
   ReductionPHI,
   ReductionOperation,
   ReductionSelect,
-  ReductionSingle
 };
 
 enum class ComplexDeinterleavingRotation {