RFR: 8260715: Lanai: MTLGraphicsConfig.m _getMTLConfigInfo optimization

[Alexey Ushakov]

Remove redundant code

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Commit messages:
 - 8260715: Lanai: MTLGraphicsConfig.m _getMTLConfigInfo optimization

Changes: https://git.openjdk.java.net/lanai/pull/196/files
 Webrev: https://webrevs.openjdk.java.net/?repo=lanai&pr=196&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260715
  Stats: 10 lines in 1 file changed: 0 ins; 10 del; 0 mod
  Patch: https://git.openjdk.java.net/lanai/pull/196.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/196/head:pull/196

PR: https://git.openjdk.java.net/lanai/pull/196