hvm: handle PoD and grant pages in HVMOP_get_mem_type

hvm: handle PoD and grant pages in HVMOP_get_mem_type

During kexec in a ballooned PVonHVM guest the new kernel needs to check
each pfn if its backed by a mfn to find ballooned pages. Currently all
PoD and grant pages will appear as HVMMEM_mmio_dm, so the new kernel has
to assume they are ballooned. This is wrong: PoD pages may turn into
real RAM at runtime, grant pages are also RAM.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>