iommu/amd: Cache pdev pointer to root-bridge

At some point pci_get_bus_and_slot started to enable
interrupts. Since this function is used in the
amd_iommu_resume path it will enable interrupts on resume
which causes a warning. The fix will use a cached pointer
to the root-bridge to re-enable the IOMMU in case the BIOS
is broken.

Cc: stable@vger.kernel.org
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 2452f3b..2435555 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -481,6 +481,9 @@
 	/* Pointer to PCI device of this IOMMU */
 	struct pci_dev *dev;
 
+	/* Cache pdev to root device for resume quirks */
+	struct pci_dev *root_pdev;
+
 	/* physical address of MMIO space */
 	u64 mmio_phys;
 	/* virtual address of MMIO space */