RFR: 8255287: aarch64: fix SVE patterns for vector shift count

[Fei Yang]

SVE patterns for vector shift count cannot be matched due to bad matching rules.
Also code gen is not correct in certain cases for vlslS_imm and vlsrS_imm.
Please refer to JDK-8255287 for details.
Patch passed tier1 tests using QEMU system emulator which supports SVE.

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Commit messages:
 - 8255287: aarch64: fix SVE patterns for vector shift count

Changes: https://git.openjdk.java.net/jdk/pull/827/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=827&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255287
  Stats: 149 lines in 7 files changed: 109 ins; 0 del; 40 mod
  Patch: https://git.openjdk.java.net/jdk/pull/827.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/827/head:pull/827

PR: https://git.openjdk.java.net/jdk/pull/827