RFR: 8282534: Remove redundant null check in ChaCha20Cipher.engineInit

[Andrey Turbanov]

8282534: Remove redundant null check in ChaCha20Cipher.engineInit

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

Commit messages:
 - [PATCH] Remove redundant null check in ChaCha20Cipher.engineInit

Changes: https://git.openjdk.java.net/jdk/pull/7424/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7424&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282534
  Stats: 9 lines in 1 file changed: 0 ins; 6 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7424.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7424/head:pull/7424

PR: https://git.openjdk.java.net/jdk/pull/7424