RFR: 8371649: AArch64: redundant OrderAccess::fence in ZBarrierSetAssembler::patch_barrier_relocation

[Evgeny Astigeevich]

The instruction cache maintenance function internally handles any required barriers.
This means we don't need any before calling it.
This PR removes a redundant OrderAccess::fence in ZBarrierSetAssembler::patch_barrier_relocation.

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Commit messages:
 - 8371649: AArch64: redundant OrderAccess::fence in ZBarrierSetAssembler::patch_barrier_relocation

Changes: https://git.openjdk.org/jdk/pull/28244/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28244&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8371649
  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/28244.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28244/head:pull/28244

PR: https://git.openjdk.org/jdk/pull/28244