RFR: 8329358: GenZGC: Remove the unused method ZPointer::set_remset_bits

[Guoxiong Li]

Hi all,

This patch removes the unused method `ZPointer::set_remset_bits`. It seems that we don't need to set two remembered bits at the same time.

Thanks for taking the time to review.

Best Regards,
-- Guoxiong

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Commit messages:
 - JDK-8329358

Changes: https://git.openjdk.org/jdk/pull/18559/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18559&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329358
  Stats: 10 lines in 2 files changed: 0 ins; 8 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/18559.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18559/head:pull/18559

PR: https://git.openjdk.org/jdk/pull/18559