arm/arm64: Factor out ptrauth vcpu feature setup

In the interest of readability, factor out the vcpu feature setup
for ptrauth into a separate function.

Also, because aarch32 doesn't have this feature or the related
command line options anyway, move the actual code into aarch64/.

Since ARM_VCPU_PTRAUTH_FEATURE is only there to make the ptrauth
feature setup code compile on arm, it is no longer needed: inline
and remove it.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
4 files changed