Revert "Add support for single reductions in ComplexDeinterleavingPass (#112875)"
This reverts commit b3eede5e1fa7ab742b86e9be22db7bccd2505b8a.
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