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

[Pengcheng Wang via cfe-commits]

https://github.com/wangpc-pp commented:

Please add a release note to `llvm/docs/ReleaseNotes.md` around line 247:
```diff
### Changes to the RISC-V Backend
...
+ * Updated the experimental `Zvzip` extension to the v0.3 draft specification.
```

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