iommu/vt-d: Use BUS_NOTIFY_REMOVED_DEVICE in hotplug path

In the PCI hotplug path of the Intel IOMMU driver, replace
the usage of the BUS_NOTIFY_DEL_DEVICE notifier, which is
executed before the driver is unbound from the device, with
BUS_NOTIFY_REMOVED_DEVICE, which runs after that.

This fixes a kernel BUG being triggered in the VT-d code
when the device driver tries to unmap DMA buffers and the
VT-d driver already destroyed all mappings.

Reported-by: Stefani Seibold <stefani@seibold.net>
Cc: stable@vger.kernel.org # v4.3+
Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 986a53e..a2e1b7f 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4367,7 +4367,7 @@
 				rmrru->devices_cnt);
 			if(ret < 0)
 				return ret;
-		} else if (info->event == BUS_NOTIFY_DEL_DEVICE) {
+		} else if (info->event == BUS_NOTIFY_REMOVED_DEVICE) {
 			dmar_remove_dev_scope(info, rmrr->segment,
 				rmrru->devices, rmrru->devices_cnt);
 		}
@@ -4387,7 +4387,7 @@
 				break;
 			else if(ret < 0)
 				return ret;
-		} else if (info->event == BUS_NOTIFY_DEL_DEVICE) {
+		} else if (info->event == BUS_NOTIFY_REMOVED_DEVICE) {
 			if (dmar_remove_dev_scope(info, atsr->segment,
 					atsru->devices, atsru->devices_cnt))
 				break;