arm64: Remove CONFIG_ARM64_CNP

Now that all the users of CnP are gone, let's perform a final
cleanup by removing the Kconfig entry, the CPU feature, and
the system_supports_cnp() helper.

The only traces left of CnP are ID register definitions, the feature
detection, and the bit definitions. All of which serve as documentation
and can be safely kept.

Signed-off-by: Marc Zyngier <maz@kernel.org>
3 files changed