iommu/amd: Prevent binding other PCI drivers to IOMMU PCI devices

AMD IOMMU driver makes use of IOMMU PCI devices, so prevent binding other
PCI drivers to IOMMU PCI devices.

This fixes a bug reported by Boris that system suspend/resume gets broken
on AMD platforms. For more information, please refer to:
	https://lkml.org/lkml/2015/9/26/89

Fixes: 991de2e5

 ("PCI, x86: Implement pcibios_alloc_irq() and pcibios_free_irq()")
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>