KVM: arm64: Add three sets of flags to the vcpu state

It so appears that each of the vcpu flags is really belonging to
one of three categories:

- a configuration flag, set once and for all
- an input flag generated by the kernel for the hypervisor to use
- a state flag that is only for the kernel's own bookkeeping

As we are going to split all the existing flags into these three
sets, introduce all three in one go.

No functional change other than a bit of bloat...

Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>