KVM: arm/arm64: Fix vGICv2 KVM_DEV_ARM_VGIC_GRP_CPU/DIST_REGS

For VGICv2 save and restore the CPU interface registers
are accessed. Restore the modality which has been altered.
Also explicitly set the iodev_type for both the DIST and CPU
interface.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>