8248671: AArch64: Remove unused variables

Remove unused variables in the AArch64 backend. Detected by compiling with MSVC, which warns about them.

Co-authored-by: Bernhard Urban-Forster <burban@openjdk.org>
Backport-of: dff37f89c5db93ce12f45334c4ab1d02390dea95
2 files changed