KVM: arm: page logging 2nd stage fault handling

This patch adds support for 2nd stage page fault handling while dirty page
logging. On huge page faults, huge pages are dissolved to normal pages, and
rebuilding of 2nd stage huge pages is blocked. In case migration is
canceled this restriction is removed and huge pages may be rebuilt again.

Signed-off-by: Mario Smarduch <m.smarduch@samsung.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>