[llvm] [RISCV] Prefer QC_EXTU to ANDI for certain 12-bit mask immediates (PR #143838)

[Sudharsan Veeravalli via llvm-commits]

svs-quic wrote:

> Can you reread your commit message, looks like you dropped a word in the second paragraph.

Done. Hopefully it reads better now.

https://github.com/llvm/llvm-project/pull/143838