KVM: arm64: Make most GICv3 accesses UNDEF if they trap

KVM: arm64: Make most GICv3 accesses UNDEF if they trap

We don't expect to trap any GICv3 register for host handling,
apart from ICC_SRE_EL1 and the SGI registers. If they trap,
that's because the guest is playing with us despite being
told it doesn't have a GICv3.

If it does, UNDEF is what it will get.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240827152517.3909653-10-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>