RFR: 8365146: Remove LockingMode related code from ppc64 [v2]

[Fredrik Bredberg]

> Since the integration of [JDK-8359437](https://bugs.openjdk.org/browse/JDK-8359437) the `LockingMode` flag can no longer be set by the user, instead it's declared as `const int LockingMode = LM_LIGHTWEIGHT;`. This means that we can now safely remove all `LockingMode` related code from all platforms.
> 
> This PR removes `LockingMode` related code from the **ppc64le** platform.
> 
> When all the `LockingMode` code has been removed from all platforms, we can go on and remove it from shared (non-platform specific) files as well. And finally remove the `LockingMode` variable itself.

Fredrik Bredberg has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into 8365146_remove_lockingmode_ppc64
 - 8365146: Remove LockingMode related code from ppc64

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/26697/files
  - new: https://git.openjdk.org/jdk/pull/26697/files/e909d06d..e9c74f13

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26697&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26697&range=00-01

  Stats: 26680 lines in 689 files changed: 16192 ins; 8264 del; 2224 mod
  Patch: https://git.openjdk.org/jdk/pull/26697.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26697/head:pull/26697

PR: https://git.openjdk.org/jdk/pull/26697