lazy-pages: start handling remaining pages if IOVs list is not empty

The copied_pages and total_pages may be different because the process may
drop parts of its address space. And the IOVs list will be empty iff we are
done with the process.

travis-ci: success for lazy-pages: add non-#PF events handling (rev2)
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>