[jdk21u-dev] RFR: 8331393: AArch64: u32 _partial_subtype_ctr loaded/stored as 64

[Boris Ulasevich]

Clean backport. A small change to use properly sized store/load instructions.
Affects only: AARCH fastdebug.
Tested: jtreg (hotspot&jdk) tier 1-3

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Commit messages:
 - Backport f215899a088d1abe86adccf0e65a073189272ddd

Changes: https://git.openjdk.org/jdk21u-dev/pull/949/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=949&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331393
  Stats: 9 lines in 2 files changed: 0 ins; 7 del; 2 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/949.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/949/head:pull/949

PR: https://git.openjdk.org/jdk21u-dev/pull/949