RFR: 8349632: RISC-V: Add Zfa fminm/fmaxm

[Anjian Wen]

Add RISCV zfa extension fminm/fmaxm
This two new Floating-point instructions can deal with NaN input directly, which can decrease instructions when calculate min or max

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Commit messages:
 - 8349632: RISC-V: Add Zfa fminm/fmaxm
 - JDK-8349632: RISC-V: Add Zfa fminm/fmaxm
 - 8349632: RISC-V: Add Zfa fminm/fmaxm
 - JDK-8349632: RISCV: Add Zfa fminm/fmaxm
 - 8349632:RISC-V: Add Zfa fminm/fmaxm

Changes: https://git.openjdk.org/jdk/pull/23509/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23509&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8349632
  Stats: 80 lines in 2 files changed: 80 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/23509.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23509/head:pull/23509

PR: https://git.openjdk.org/jdk/pull/23509