fs-tests: integck: make power cut mode work

fs-tests: integck: make power cut mode work

This is a dirty patch - it makes many changes, but I simply had no
time to split it. And because this test is something no one except me
and Adrian cares about, I do not want to spend too much time creating
nice patches. Anyway, this patch make the power cut testing mode work.

Now you can run the test like "./integck /mnt/ubifs -p" and it will
run recover from emulated power cut failures and continue forever,
untill an unexpected issue is met.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>