ANDROID: KVM: arm64: Fix prefaulting when breaking PUD blocks

When breaking PUD block mappings in the host's stage-2, we fail to
prefault the last level entries as the corresponding PMD table is
temporarily installed as invalid to avoid an unecessary TLBI.

This can break partner use-cases which rely on prefaulting, so let's
bite the bullet and accept the sub-optimal TLBI only in this specific
case.

Bug: 278749606
Bug: 308373293
Change-Id: I55a1fb7c91b869bff1a486528dad8ab3dedb4b38
Signed-off-by: Quentin Perret <qperret@google.com>