[foreign-memaccess+abi] RFR: Rename parameter names

[Per Minborg]

This PR renames parameter names to be more consistent across all classes.

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Commit messages:
 - Rename parameter names

Changes: https://git.openjdk.org/panama-foreign/pull/726/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=726&range=00
  Stats: 145 lines in 13 files changed: 2 ins; 3 del; 140 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/726.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign pull/726/head:pull/726

PR: https://git.openjdk.org/panama-foreign/pull/726