ANDROID: KVM: arm64: Move vgic state between host and hypervisor vcpu structures

Since the world switch vgic code operates on the hypervisor data
structure, move the state back and forth between the host and
hypervisor vcpu.

This is currently limited to the VMCR and APR registers, but further
patches will deal with the rest of the state.

Note that some of the control settings (such as SRE) are always
set to the same value. This will eventually be moved to initialisation
time for the hypervisor structures.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 233587962
Change-Id: I8a3a9009ce3408fe06ea272504f4f71c3d47b7bf