x86, AMD, PCI: Add AMD northbridge PCI device id for CPU families 12h and 14h

This patch adds the PCI northbridge device id for AMD CPU
families 12h and 14h. Both families have implemented the same
PCI northbridge device.

There are some future use cases that use this PCI device and
we would like to clarify its naming.

Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: xen-devel@lists.xensource.com <xen-devel@lists.xensource.com>
Cc: Keir Fraser <keir@xen.org>
Cc: Jan Beulich <JBeulich@novell.com>
LKML-Reference: <20110106165107.GL4739@erda.amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>