[AMDGPU] Enable machine verification after AMDGPUISelDAGToDAG This was introduced in D32628 but it does not seem to be required any more. At least it does not show any problems in check-llvm in an LLVM_ENABLE_EXPENSIVE_CHECKS build. Differential Revision: https://reviews.llvm.org/D110692 GitOrigin-RevId: f9b68304a22ef82d827d282dd9014efc2e7ac875