RFR: 8366037: Remove oopDesc::mark_addr()

[Kim Barrett]

Please review this change that removes the function oopDesc::mark_addr().
It's kind of a suspicious function, since it is casting away the volatile for
a location that has concurrent reads and writes. But there isn't any code that
examines the value at the obtained address. Instead, it's just used as the
base address for a few prefetches. We change those places accordingly, and
remove the now unused mark_addr function.

Testing: mach5 tier1

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Commit messages:
 - remove mark_addr and fix callers

Changes: https://git.openjdk.org/jdk/pull/26914/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26914&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8366037
  Stats: 11 lines in 4 files changed: 1 ins; 5 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/26914.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26914/head:pull/26914

PR: https://git.openjdk.org/jdk/pull/26914