x86/amd_nb: Add Fam17h Data Fabric as "Northbridge"

AMD Fam17h uses a Data Fabric component instead of a traditional
Northbridge. However, the DF is similar to a NB in that there is one per
die and it uses PCI config D18Fx registers. So let's reuse the existing
AMD_NB infrastructure for Data Fabrics.

Signed-off-by: Yazen Ghannam <Yazen.Ghannam@amd.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/1478812257-5424-4-git-send-email-Yazen.Ghannam@amd.com
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>