RFR: 8367706: Remove redundant register used by cmove in C1 LIR generation

[lusou-zhangquan]

This PR removes redundant temp register used by cmove in C1 LIRGenerator::do_LookupSwitch and LIRGenerator::do_TableSwitch. The issue [8367706](https://bugs.openjdk.org/browse/JDK-8367706) is reported by me and it's my pleasure to fix it.

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Commit messages:
 - 8367706: Remove redundant register used by cmove in C1 LIR generation

Changes: https://git.openjdk.org/jdk/pull/27307/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27307&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8367706
  Stats: 8 lines in 1 file changed: 2 ins; 6 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27307.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27307/head:pull/27307

PR: https://git.openjdk.org/jdk/pull/27307