hvmloader: PA range 0xfc000000-0xffffffff should be UC

hvmloader: PA range 0xfc000000-0xffffffff should be UC

Rather than leaving the range from PCI_MEM_END (0xfc000000) to 4G
uncovered, we should include this in the UC range created for the (low)
PCI range. Besides being more correct, this also has the advantage that
with the way pci_setup() currently works the range will always be
mappable with a single variable range MTRR (rather than from 2 to 5
depending on how much the lower boundary gets shifted down to
accommodate all devices).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>