[foreign-memaccess+abi] RFR: Fix typo in vector test template

[Maurizio Cimadamore]

When fixing vector tests as part of https://git.openjdk.org/panama-foreign/pull/786 I have accidentally introduced a typo. This patch fixes that.

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Commit messages:
 - Fix typo in vector test template

Changes: https://git.openjdk.org/panama-foreign/pull/789/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=789&range=00
  Stats: 31 lines in 31 files changed: 0 ins; 0 del; 31 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/789.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign pull/789/head:pull/789

PR: https://git.openjdk.org/panama-foreign/pull/789