PCI: Support BAR sizes up to 8GB

This is needed for some of the Xeon Phi type systems.

[bhelgaas: added Nikhil, use ARRAY_SIZE() to connect with decl, folded in
Kevin's "order < 0" fix to ARRAY_SIZE() usage]
Signed-off-by: Nikhil P Rao <nikhil.rao@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>