[llvm-objdump] Move --start-address >= --stop-address check out of the
Move it into main function so the checking is effective for all actions
user may do with llvm-objdump; notably, -r and -s in addition to existing -d.
Match GNU behavior.
Reviewers: jhenderson, grimar, MaskRay, rupprecht
Differential Revision: https://reviews.llvm.org/D63631