ANDROID: KVM: arm64: Always check state from host_ack_unshare()

Similar to how we failed to cross-check the state from the completer's
PoV on the hyp_ack_unshare() path, we fail to do so from
host_ack_unshare().

This shouldn't cause problems in practice as this can only be called on
the guest_unshare_host() path, and guest currently don't have the
ability to share their pages with anybody other than the host. But this
again is rather fragile, so let's simply do the proper check -- it isn't
very costly thanks to the hyp_vmemmap optimisation.

Bug: 381409114
Change-Id: I3770b7db55c579758863e41f50ab30f6a8bb4a0c
Signed-off-by: Quentin Perret <qperret@google.com>