RFR: 8259584: SuperWord::fix_commutative_inputs checks in_bb(fin1) instead of in_bb(fin2)

[Vladimir Kozlov]

Fix typo. Note, this change does not affect product because this code is not executed after JDK-8251994 fix: 
https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/superword.cpp#L519

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Commit messages:
 - 8259584: SuperWord::fix_commutative_inputs checks in_bb(fin1) instead of in_bb(fin2)

Changes: https://git.openjdk.java.net/jdk/pull/2299/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2299&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8259584
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2299.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2299/head:pull/2299

PR: https://git.openjdk.java.net/jdk/pull/2299