[riscv-port-jdk17u:riscv-port] RFR: 8307150: RISC-V: Remove remaining StoreLoad barrier with UseCondCardMark for Serial/Parallel GC

[Feilong Jiang]

Hi,
Please review this clean backport of [JDK-8307150](https://bugs.openjdk.org/browse/JDK-8307150) to riscv-port-jdk17u.
Same as the mainline, this `StoreLoad` barrier is no longer needed after the removal of CMS.

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Commit messages:
 - 8307150: RISC-V: Remove remaining StoreLoad barrier with UseCondCardMark for Serial/Parallel GC

Changes: https://git.openjdk.org/riscv-port-jdk17u/pull/55/files
 Webrev: https://webrevs.openjdk.org/?repo=riscv-port-jdk17u&pr=55&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307150
  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/riscv-port-jdk17u/pull/55.diff
  Fetch: git fetch https://git.openjdk.org/riscv-port-jdk17u.git pull/55/head:pull/55

PR: https://git.openjdk.org/riscv-port-jdk17u/pull/55