RFR: 8285266: compiler/intrinsics/sha/cli/TestUseSHA256IntrinsicsOptionOnUnsupportedCPU.java fails after JDK-8284563

[Vladimir Kozlov]

Changes for #8258 renamed `sha256` aarch64 feature to `sha2`. Unfortunately this name is used by testing to determine if a feature is supported: [IntrinsicPredicates.java#L78](https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/compiler/testlibrary/sha/predicate/IntrinsicPredicates.java#L78)

I reverted the name back to fix the issue. Tested tier1-3.

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Commit messages:
 - 8285266: compiler/intrinsics/sha/cli/TestUseSHA256IntrinsicsOptionOnUnsupportedCPU.java fails after JDK-8284563

Changes: https://git.openjdk.java.net/jdk/pull/8324/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8324&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8285266
  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8324.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8324/head:pull/8324

PR: https://git.openjdk.java.net/jdk/pull/8324