iommu/amd: Add device errata handling

Add infrastructure for errata-handling and handle two known
erratas in the IOMMUv2 code.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index c39988f..6ad8b10 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -404,6 +404,7 @@
 	} ats;				  /* ATS state */
 	bool pri_tlp;			  /* PASID TLB required for
 					     PPR completions */
+	u32 errata;			  /* Bitmap for errata to apply */
 };
 
 /*