[riscv-port-jdk17u:riscv-port] RFR: 8287425: Remove unnecessary register push for MacroAssembler::check_klass_subtype_slow_path

[Xiaolin Zheng]

This is another-half backport (RISC-V part only) of [JDK-8287425](https://bugs.openjdk.org/browse/JDK-8287425). The original patch is at [1].

This patch can interestingly fix an issue with async-profiler [2], and has been backported to JDK17/JDK11u. But when backporting to JDK17, the RISC-V part of this patch was dropped [3] since we did not have the RISC-V backend. Now that we have the RISC-V port of JDK17, the missing part needs a backport as well.

Tested on unmatched, hotspot tier1~2 (fastdebug). More tiers are on the way.

[1] https://github.com/openjdk/jdk/commit/b5a646ee6cfd432cef6b7e69a177959227a38ace
[2] https://github.com/jvm-profiling-tools/async-profiler/issues/673#issuecomment-1316738564
[3] https://github.com/openjdk/jdk17u-dev/pull/672

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Commit messages:
 - 8287425: Remove unnecessary register push for MacroAssembler::check_klass_subtype_slow_path

Changes: https://git.openjdk.org/riscv-port-jdk17u/pull/16/files
 Webrev: https://webrevs.openjdk.org/?repo=riscv-port-jdk17u&pr=16&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8287425
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/riscv-port-jdk17u/pull/16.diff
  Fetch: git fetch https://git.openjdk.org/riscv-port-jdk17u pull/16/head:pull/16

PR: https://git.openjdk.org/riscv-port-jdk17u/pull/16