RFR: 8362596: RISC-V: Improve _vectorizedHashCode intrinsic

[Yuri Gaevsky]

This is a micro-optimization for RISC-V SpacemiT K1 CPU to fix [encountered performance regression](https://github.com/openjdk/jdk/pull/17413#issuecomment-3082664335).

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Commit messages:
 - 8362596: RISC-V: Improve _vectorizedHashCode intrinsic

Changes: https://git.openjdk.org/jdk/pull/26409/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26409&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8362596
  Stats: 6 lines in 1 file changed: 1 ins; 3 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/26409.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26409/head:pull/26409

PR: https://git.openjdk.org/jdk/pull/26409