RFR: 8252494: C2: TypeAryPtr::cast_to_autobox_cache does not use ptr_type

[Roberto Castañeda Lozano]

Remove dead definition of `ptr_type` in `TypeAryPtr::cast_to_autobox_cache`. Also remove unnecessary `cache` parameter
(always true) for simplicity.

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Commit messages:
 - 8252494: C2: TypeAryPtr::cast_to_autobox_cache does not use ptr_type

Changes: https://git.openjdk.java.net/jdk/pull/106/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=106&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8252494
  Stats: 6 lines in 2 files changed: 0 ins; 1 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/106.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/106/head:pull/106

PR: https://git.openjdk.java.net/jdk/pull/106