RFR: 8342953: RISC-V: Fix definition of RISCV_HWPROBE_EXT_ZVFHMIN

[Fei Yang]

Hi,

Please review this trivial change correcting definition of macro `RISCV_HWPROBE_EXT_ZVFHMIN`.

This macro is supposed to be used when making a `hwprobe` linux syscall for detecting the Zvfhmin extension. Current definition yields a negative 32bits value, messing up hwprobe result when Zvfhmin extension presents. Replace it by using a 1ULL bit shift value as done in kernel upstream [1]. Although it is not used by the JVM for now, it's better to correct it for consistency with the kernel upstream.

[1] https://github.com/torvalds/linux/commit/5ea6764d9095e234b024054f75ebbccc4f0eb146

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Commit messages:
 - 8342953: RISC-V: Fix definition of RISCV_HWPROBE_EXT_ZVFHMIN

Changes: https://git.openjdk.org/jdk/pull/21680/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21680&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342953
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21680.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21680/head:pull/21680

PR: https://git.openjdk.org/jdk/pull/21680