ANDROID: KVM: arm64: Invoke the POST callback walker on the stage2 annotation install

Commit 5abca844 introduces stage-2
coalescing for the host pagetables but the code path is not triggered
because of a missing flag that has been removed upstream.
Add back a missing flag for the walker to make sure that we zap the
non-refocunted page table pages on our way up. The zapping of the page
table pages into blocks happens when we donate the pages from (HYP ->
HOST).

Bug: 278749606
Bug: 325040553
Change-Id: I5aea0764f07baa90f84da3a5f7e0462ba6597ca8
Signed-off-by: Sebastian Ene <sebastianene@google.com>