cpu: aarch64: fp16 postops: disable ACL post ops for fp16

[fadara01]

Description

The oneDNN API specifies that post ops need to (always) be executed in fp32, but ACL executes them in f16 (when running in fp16 mode) which caused a lot of conv+relu benchdnn tests to fail.

Fixes # (#1499)

Checklist

General

• [ YES ] Do all unit and benchdnn tests (make test and make test_benchdnn_*) pass locally for each commit?
• [ YES ] Have you formatted the code using clang-format?

Performance improvements

• [ N/A] Have you submitted performance data that demonstrates performance improvements?

New features

• [ N/A] Have you published an RFC for the new feature?
• [ N/A] Was the RFC approved?
• [ N/A] Have you added relevant tests?

Bug fixes

• [ YES] Have you included information on how to reproduce the issue (either in a github issue or in this PR)?
• [ N/A] Have you added relevant regression tests?

[igorsafo]

Hi @fadara01 ,
The changes landed into rls-v2.7, rls-v3.0 and master. Thank you for your contribution!