RFR: 8294671: Remove unused CardValues::last_card

Fri Sep 30 12:30:21 UTC 2022

Simple change of removing dead code.

Test: hotspot_gc

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Commit messages:
 - card-table-remove-last

Changes: https://git.openjdk.org/jdk/pull/10510/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10510&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294671
  Stats: 3 lines in 2 files changed: 0 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/10510.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10510/head:pull/10510

PR: https://git.openjdk.org/jdk/pull/10510