Combining pre-copy (pre-dump) and post-copy (lazy-pages) mode showed a
problem in the function page_pipe_split_ppb(). The function is used to
split the page-pipe-buffer so that it only contains the IOVs request
from the restore side during lazy restore.

Unfortunately it only splits the leading IOVs out of the
page-pipe-buffer and not the trailing:

Before split for requested address 0x7f27284d1000:

 page-pipe: ppb->iov 0x7f0f74d93040
 page-pipe: 		0x7f27282bb000 1
 page-pipe: 		0x7f27284d1000 1
 page-pipe: 		0x7f27284dd000 2

After split:

 page-pipe: ppb->iov 0x7f0f74d93050
 page-pipe: 		0x7f27284d1000 1
 page-pipe: 		0x7f27284dd000 2

and:

 page-pipe: ppb->iov 0x7f0f74d93040
 page-pipe: 		0x7f27282bb000 1

This patch keeps on splitting the page-pipe-buffer until it contains
only the requested address with the requested length.

After split (still trying to load 0x7f27284d1000):

 page-pipe: ppb->iov 0x7f0f74d93050
 page-pipe: 		0x7f27284d1000 1

and:

 page-pipe: ppb->iov 0x7f0f74d93040
 page-pipe: 		0x7f27282bb000 1

and:

 page-pipe: ppb->iov 0x7f0f74d93060
 page-pipe: 		0x7f27284dd000 2

v2:
 - moved declarations to the declaration block
Signed-off-by: Adrian Reber <areber@redhat.com>
Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>