ANDROID: KVM: arm64: Fix the host ownership later

The fix_host_ownership() path walks the hypervisor's stage-1 page-table
to adjust the host's stage-2 accordingly. However, this is done before
the hyp stage-1 refcount has been fixed up, and before the hyp percpu
fixmap has been created. This all works right now as we start off with
an empty host stage-2, so none of the changes require the usage of the
fixmap for e.g. CMOs.

To prepare the ground for doing fix_host_ownership() with a non-empty
page-table, finalize the hyp stage-1 upfront.

Bug: 264070847
Change-Id: I6aff3ac2f835be3fb3fba7660540c0a9b99c097d
Signed-off-by: Quentin Perret <qperret@google.com>