RFR: 8330095: RISC-V: Remove obsolete vandn_vi instruction

[Ludovic Henry]

On Thu, 11 Apr 2024 11:17:49 GMT, Gui Cao <gcao at openjdk.org> wrote:

> Hi, We notice that the `vandn_vi` instruction is defined in the current code and is not used anywhere, it is not available in the riscv-crypto Release-1.0.0 manual. The `vandn_vi` instruction is present in earlier riscv-crypto manual, but the `vandnvi` has been removed from the https://github.com/riscv/riscv-crypto/commit/82a02f09668adb18dfee5dfc45a0ce7d3af10103 commit.
> 
> ### Testing
> - [x]  fastdebug build successfully

Marked as reviewed by luhenry (Committer).

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PR Review: https://git.openjdk.org/jdk/pull/18737#pullrequestreview-1995427980