[jdk25u-dev] RFR: 8373998: RISC-V: simple optimization of ConvHF2F

[Fei Yang]

Hi all,

This pull request contains a backport of commit [5eb87749](https://github.com/openjdk/jdk/commit/5eb8774909bd250c7ff8cfc56506a949b547bda2) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Hamlin Li on 19 Dec 2025 and was reviewed by Fei Yang and Dingli Zhang.

Thanks!

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Commit messages:
 - Backport 5eb8774909bd250c7ff8cfc56506a949b547bda2

Changes: https://git.openjdk.org/jdk25u-dev/pull/116/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk25u-dev&pr=116&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8373998
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk25u-dev/pull/116.diff
  Fetch: git fetch https://git.openjdk.org/jdk25u-dev.git pull/116/head:pull/116

PR: https://git.openjdk.org/jdk25u-dev/pull/116