[clang] [llvm] [RISCV] Update Zvzip support to v0.3 (PR #210603)

[Pengcheng Wang via llvm-commits]

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wangpc-pp wrote:

`IsVZIP` is a dead variable now since `VZIP_VV` doesn't set `ReadsPastVL` (only vunzipe.v/vunzipo.v do). We can remove `!IsVZIP` in line 1126.

https://github.com/llvm/llvm-project/pull/210603