PCI: vmd: Add bus 224-255 restriction decode

VMD bus restrictions are required when IO fabric is multiplexed such
that VMD cannot use the entire bus range. This patch adds another bus
restriction decode bit that can be set by firmware to restrict the VMD
bus range to between 224-255.

Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>