[CodeGen] Enhance `MachineInstrSpan` to allow the end of MBB to be used.

Summary:
- Explicitly specify the parent MBB to allow the end iterator to be
  used.

Reviewers: aprantl, MatzeB, craig.topper, qcolombet

Subscribers: arsenm, jvesely, nhaehnle, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64261

llvm-svn: 365240