[riscv-port-jdk11u:riscv-port] RFR: 8339248: RISC-V: Remove li64 macro assembler routine and related code

[Gui Cao]

Hi, The same issue also exists in riscv-port-jdk11u. So I would like to backport [JDK-8339248](https://bugs.openjdk.org/browse/JDK-8339248) to riscv-port-jdk11u. with this patch ,it will save us some unnecessary runtime checks. This is a risc-v specific change, risk is low.

### Testing
- [x] Run hotspot:tier1 tests on SOPHON SG2042 (release)

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Commit messages:
 - Backport 8339248: RISC-V: Remove li64 macro assembler routine and related code

Changes: https://git.openjdk.org/riscv-port-jdk11u/pull/27/files
  Webrev: https://webrevs.openjdk.org/?repo=riscv-port-jdk11u&pr=27&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339248
  Stats: 111 lines in 5 files changed: 0 ins; 111 del; 0 mod
  Patch: https://git.openjdk.org/riscv-port-jdk11u/pull/27.diff
  Fetch: git fetch https://git.openjdk.org/riscv-port-jdk11u.git pull/27/head:pull/27

PR: https://git.openjdk.org/riscv-port-jdk11u/pull/27