[riscv-port-jdk17u:riscv-port] RFR: 8294086: RISC-V: Cleanup InstructionMark usages in the backend

[Xiaolin Zheng]

Backport one RVC-related patch (3rd, 8 in total). The remaining patches seem to be linear and cannot be submitted concurrently.

Tested along with remaining RVC patches, hotspot tier1~4 with fastdebug build.

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Commit messages:
 - 8294086: RISC-V: Cleanup InstructionMark usages in the backend

Changes: https://git.openjdk.org/riscv-port-jdk17u/pull/23/files
 Webrev: https://webrevs.openjdk.org/?repo=riscv-port-jdk17u&pr=23&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294086
  Stats: 21 lines in 3 files changed: 0 ins; 12 del; 9 mod
  Patch: https://git.openjdk.org/riscv-port-jdk17u/pull/23.diff
  Fetch: git fetch https://git.openjdk.org/riscv-port-jdk17u.git pull/23/head:pull/23

PR: https://git.openjdk.org/riscv-port-jdk17u/pull/23