iommu/amd: Init stats for iommu=pt

The IOMMUv2 driver added a few statistic counter which are
interesting in the iommu=pt mode too. So initialize the
statistic counter for that mode too.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

drivers/iommu/amd_iommu.c

@@ -3238,6 +3238,8 @@ int __init amd_iommu_init_passthrough(void)
 		attach_device(&dev->dev, pt_domain);
 	}
 
+	amd_iommu_stats_init();
+
 	pr_info("AMD-Vi: Initialized for Passthrough Mode\n");
 
 	return 0;