[llvm] [Hexagon] Define V91 ISA and Processor versions in ELF flags (PR #163631)

[Brian Cain via llvm-commits]

https://github.com/androm3da requested changes to this pull request.

Can you make corresponding changes in `ScalarBitSetTraits<ELFYAML::ELF_EF>::bitset()` in `llvm/lib/ObjectYAML/ELFYAML.cpp`?

https://github.com/llvm/llvm-project/pull/163631