RFR: Remove unnecessary init in AESGCMBench:setup

[Dongbo He]

decryptCipher will be reinitialized in decrypt, which will loses all previously-acquired state. Therefore, it's not necessary to initialize in setup.

-------------

Commit messages:
 - Remove unnecessary init in AESGCMBench:setup

Changes: https://git.openjdk.java.net/jmh-jdk-microbenchmarks/pull/8/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmh-jdk-microbenchmarks&pr=8&range=00
  Stats: 2 lines in 1 file changed: 0 ins; 2 del; 0 mod
  Patch: https://git.openjdk.java.net/jmh-jdk-microbenchmarks/pull/8.diff
  Fetch: git fetch https://git.openjdk.java.net/jmh-jdk-microbenchmarks pull/8/head:pull/8

PR: https://git.openjdk.java.net/jmh-jdk-microbenchmarks/pull/8