RFR: 8309627: Incorrect sorting of DirtyCardQueue buffers

[Kim Barrett]

Please review this simple fix to the sorting of dirty card buffers.  The
comparison function is using the difference between the card pointer to
compute the order, but is discarding all but the low 32 bits.

While I was at it, adjusted the name of the sort function.

Testing:
mach5 tier1

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Commit messages:
 - fix

Changes: https://git.openjdk.org/jdk/pull/14365/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14365&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309627
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/14365.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14365/head:pull/14365

PR: https://git.openjdk.org/jdk/pull/14365