[llvm] [RISCV] Add IsSignExtendingOpW to Zabha and Zalasr instructions. (PR #162341)

[Philip Reames via llvm-commits]

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

LGTM

(Just noting, I checked the spec documents and agree that the wording applies.)

https://github.com/llvm/llvm-project/pull/162341