RFR: 8342715: x86 unused orw instruction encoding could be removed

[hanklo6]

x86 orw(Register, Register) encoding is missing 0x66 prefix. This instruction is unused and can be removed. It was initially removed in #20901 but was re-added in #20698

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Commit messages:
 - Remove x86 orw encoding

Changes: https://git.openjdk.org/jdk/pull/21620/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21620&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342715
  Stats: 6 lines in 2 files changed: 0 ins; 6 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21620.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21620/head:pull/21620

PR: https://git.openjdk.org/jdk/pull/21620