This makes the API cleaner -- now we tell to parasite_dump_pages_seized
only two things -- whether it's pre-dump or not and, if not, whether this
is lazy dump.

And make it do all the other decisions himself.
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com>