RFR: 8328081: Remove unnecessary return statement in method `markWord::displaced_mark_helper`

[Guoxiong Li]

Hi all,

This trivial patch removes unnecessary return statement in method `markWord::displaced_mark_helper`.

Thanks for taking the time to review.

Best Regards,
-- Guoxiong

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Commit messages:
 - Remove unnecessary code.

Changes: https://git.openjdk.org/jdk/pull/18272/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18272&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328081
  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18272.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18272/head:pull/18272

PR: https://git.openjdk.org/jdk/pull/18272