[llvm] [RISCV] Fix a bug where AVL is the last MI in MBB. (PR #144668)

[Min-Yih Hsu via llvm-commits]

https://github.com/mshockwave approved this pull request.

LGTM good catch. I vaguely remember we do account for AVL being last instruction in `coalesceVSETVLI` but seems like we missed this place.

https://github.com/llvm/llvm-project/pull/144668