[riscv-port-jdk17u:riscv-port] RFR: 8301153: RISC-V: pipeline class for several instructions is not set correctly

[Gui Cao]

Hi,
Please review this backport to riscv-port-jdk17u.
Backport of [JDK-8301153](https://bugs.openjdk.org/browse/JDK-8301153). Applies cleanly.

Testing:

Tier1-3 passed without new failure on unmacthed (release).

-------------

Commit messages:
 - backport RISC-V: pipeline class for several instructions is not set correctly

Changes: https://git.openjdk.org/riscv-port-jdk17u/pull/61/files
 Webrev: https://webrevs.openjdk.org/?repo=riscv-port-jdk17u&pr=61&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8301153
  Stats: 20 lines in 1 file changed: 1 ins; 0 del; 19 mod
  Patch: https://git.openjdk.org/riscv-port-jdk17u/pull/61.diff
  Fetch: git fetch https://git.openjdk.org/riscv-port-jdk17u.git pull/61/head:pull/61

PR: https://git.openjdk.org/riscv-port-jdk17u/pull/61