KVM: arm64: pkvm: Make kvm_host_owns_hyp_mappings() robust to VHE

The kvm_host_owns_hyp_mappings() function should return true if and only
if the host kernel is responsible for creating the hypervisor stage-1
mappings. That is only possible in standard non-VHE mode, or during boot
in protected nVHE mode. But either way, none of this makes sense in VHE,
so make sure to catch this case as well, hence making the function
return sensible values in any context (VHE or not).

Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211208152300.2478542-7-qperret@google.com