xen: add explicit memblock_reserve() calls for special pages

xen: add explicit memblock_reserve() calls for special pages

Some special pages containing interfaces to xen are being reserved
implicitly only today. The memblock_reserve() call to reserve them is
meant to reserve the p2m list supplied by xen. It is just reserving
not only the p2m list itself, but some more pages up to the start of
the xen built page tables.

To be able to move the p2m list to another pfn range, which is needed
for support of huge RAM, this memblock_reserve() must be split up to
cover all affected reserved pages explicitly.

The affected pages are:
- start_info page
- xenstore ring (might be missing, mfn is 0 in this case)
- console ring (not for initial domain)

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
(cherry picked from commit 6c2681c863b24360098d1ba60f2af060a13a0561)
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
(cherry picked from commit f9918f852bb0e2cd1e7a86966e5f3d0dd25a094f)