KVM: arm64: Fix memory check in host_stage2_set_owner_locked()

I found this simple bug while preparing some patches for pKVM.
AFAICT, it should be harmless (besides crashing the kernel if it
was misbehaving)

Fixes: e94a7dea ("KVM: arm64: Move host page ownership tracking to the hyp vmemmap")
Signed-off-by: Mostafa Saleh <smostafa@google.com>
Link: https://lore.kernel.org/r/20250501162450.2784043-1-smostafa@google.com


Signed-off-by: Oliver Upton <oliver.upton@linux.dev>