iommu/amd: Add function to get IOMMUv2 domain for pdev

The AMD IOMMUv2 driver needs to get the IOMMUv2 domain
associated with a particular device. This patch adds a
function to get this information.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/drivers/iommu/amd_iommu_proto.h b/drivers/iommu/amd_iommu_proto.h
index bb5ecfe..1a7f41c 100644
--- a/drivers/iommu/amd_iommu_proto.h
+++ b/drivers/iommu/amd_iommu_proto.h
@@ -46,6 +46,7 @@
 extern int amd_iommu_domain_set_gcr3(struct iommu_domain *dom, int pasid,
 				     unsigned long cr3);
 extern int amd_iommu_domain_clear_gcr3(struct iommu_domain *dom, int pasid);
+extern struct iommu_domain *amd_iommu_get_v2_domain(struct pci_dev *pdev);
 
 #define PPR_SUCCESS			0x0
 #define PPR_INVALID			0x1