RFR: 8315070: RSIC-V: Clean up platform dependent inline headers

[Feilong Jiang]

Hi team, please review this small clean-up changes.
Inspired by [JDK-8267464](https://bugs.openjdk.org/browse/JDK-8267464), riscv port still has one place that includes platform-dependent inline header `assembler_riscv.inline.hpp`, it could be replaced with platform-independent header `asm/assembler.inline.hpp`.

Testing: 
- [x] release build on linux-riscv64
- [x] tier1 on linux-riscv64 with release build

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Commit messages:
 - update copyright
 - include platform independent file

Changes: https://git.openjdk.org/jdk/pull/15437/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15437&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315070
  Stats: 3 lines in 1 file changed: 1 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15437.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15437/head:pull/15437

PR: https://git.openjdk.org/jdk/pull/15437