[lworld] RFR: 8340794: [lworld] Follow up 8329433 for Valhalla entry points in nmethod

[Manuel Hässig]

This PR makes the necessary changes to also make the inline entry point fields in the nmethod class a `uint16_t` like JDK-8329433 did for the other entry points. Importantly, this PR preserves the default values necessary for unused entry points.

Testing:
 - [ ] tier1,tier2,tier2

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Commit messages:
 - Make valhalla entry points uint16_t

Changes: https://git.openjdk.org/valhalla/pull/2116/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=2116&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8340794
  Stats: 31 lines in 4 files changed: 7 ins; 1 del; 23 mod
  Patch: https://git.openjdk.org/valhalla/pull/2116.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2116/head:pull/2116

PR: https://git.openjdk.org/valhalla/pull/2116