arm64: Allow a capability to be checked on a single CPU

arm64: Allow a capability to be checked on a single CPU

Now that the capabilities are only available once all the CPUs
have booted, we're unable to check for a particular feature
in any subsystem that gets initialized before then.

In order to support this, introduce a local_cpu_has_cap() function
that tests for the presence of a given capability independently
of the whole framework.

Reviewed-by: Catalin Marinas <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
[ Added preemptible() check ]
Signed-off-by: Suzuki K Poulose <[email protected]>
[will: remove duplicate initialisation of caps in this_cpu_has_cap]
Signed-off-by: Will Deacon <[email protected]>