[riscv-port-jdk11u:riscv-port] RFR: 8283865: riscv: Break down -XX:+UseRVB into seperate options for each bitmanip extension

[Gui Cao]

Hi, The same issue[1] also exists in the riscv-port-jdk11u. According to the spec,  we need to break down UseRVB into two individual options UseZba and UseZbb to enable or disable Zba and Zbb respectively. 

Linux RISCV64 release hotspot/jdk tier1 tests are passed on QEMU with following options:
 - [x] +UseZba && +UseZbb
 - [x] +UseZba && -UseZbb
 - [x] -UseZba && +UseZbb

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Commit messages:
 - Backport JDK-8283865: riscv: Break down -XX:+UseRVB into seperate options for each bitmanip extension

Changes: https://git.openjdk.org/riscv-port-jdk11u/pull/13/files
  Webrev: https://webrevs.openjdk.org/?repo=riscv-port-jdk11u&pr=13&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8283865
  Stats: 123 lines in 8 files changed: 5 ins; 11 del; 107 mod
  Patch: https://git.openjdk.org/riscv-port-jdk11u/pull/13.diff
  Fetch: git fetch https://git.openjdk.org/riscv-port-jdk11u.git pull/13/head:pull/13

PR: https://git.openjdk.org/riscv-port-jdk11u/pull/13