vfio: Use device_iommu_capable()

Use the new interface to check the capabilities for our device
specifically.
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4ea5eb64246f1ee188d1a61c3e93b37756932eb7.1656092606.git.robin.murphy@arm.comSigned-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/vfio.c

@@ -605,7 +605,7 @@ int vfio_register_group_dev(struct vfio_device *device)
 	 * VFIO always sets IOMMU_CACHE because we offer no way for userspace to
 	 * restore cache coherency.
 	 */
-	if (!iommu_capable(device->dev->bus, IOMMU_CAP_CACHE_COHERENCY))
+	if (!device_iommu_capable(device->dev, IOMMU_CAP_CACHE_COHERENCY))
 		return -EINVAL;
 
 	return __vfio_register_dev(device,