RFR: 8367694: Fix jtreg test failure when Intel APX is enabled for KNL platforms

[Srinivas Vamsi Parasa]

This goal of this PR is fix the jtreg test failure observed in compiler test: `test/hotspot/jtreg/compiler/loopopts/superword/TestDependencyOffsets.java`

The test failure is occurring specifically for the tests with ids = {avx512-v064-A, avx512-v064-U, avx512-v032-A, avx512-v032-U}. These tests are run with KNL hardware features enabled (`-XX:+UseKNLSetting`). 

The two main causes of test failure are: 
1. KNL does not support Intel APX. Currently, APX is not turned off when using KNL. This PR fixes this issue.
2. BMI2 instructions like sarxl are encoded incorrectly with `uses_vl=true` (use vector length). This PR fixes the encoding to use the correct one:`uses_vl=false`.

After fixing these two bugs, `TestDependencyOffsets.java` is passing using the SDE emulator when APX is enabled.

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Commit messages:
 - Update assembler_x86.cpp
 - 8367694: Fix jtreg test failure when Intel APX is enabled for KNL platforms

Changes: https://git.openjdk.org/jdk/pull/27299/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27299&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8367694
  Stats: 14 lines in 2 files changed: 1 ins; 0 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/27299.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27299/head:pull/27299

PR: https://git.openjdk.org/jdk/pull/27299