x86/amd-iommu: Fix PCI hotplug with passthrough mode

The device change notifier is initialized in the dma_ops
initialization path. But this path is never executed for
iommu=pt. Move the notifier initialization to IOMMU hardware
init code to fix this.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

arch/x86/kernel/amd_iommu_init.c

@@ -1285,6 +1285,8 @@ static int __init amd_iommu_init(void)
 	if (ret)
 		goto free;
 
+	amd_iommu_init_notifier();
+
 	enable_iommus();
 
 	if (iommu_pass_through)