RFR: 8331360: RISCV: u32 _partial_subtype_ctr loaded/stored as 64

[Robbin Ehn]

Hi, please consider.

We should use incrementw() for these.

Sanity tested, running t1.

Thanks, Robbin

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Commit messages:
 - use incw

Changes: https://git.openjdk.org/jdk/pull/19010/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19010&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331360
  Stats: 9 lines in 2 files changed: 0 ins; 7 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/19010.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19010/head:pull/19010

PR: https://git.openjdk.org/jdk/pull/19010