hvmloader: Change memory relocation loop when overlap with PCI hole

hvmloader: Change memory relocation loop when overlap with PCI hole

Change the way we relocate the memory page if they overlap with pci
hole.  Use new map space (XENMAPSPACE_gmfn_range) to move the loop
into xen.

This code usually get triggered when a device is pass through to a
guest and the PCI hole has to be extended to have enough room to map
the device BARs.  The PCI hole will starts lower and it might overlap
with some RAM that has been alocated for the guest. That usually
happen if the guest has more than 4G of RAM.  We have to relocate
those pages in high mem otherwise they won't be accessible.

Signed-off-by: Jean Guyader <jean.guyader@eu.citrix.com>
Committed-by: Keir Fraser <keir@xen.org>