iommu/vt-d: Use BUS_NOTIFY_REMOVED_DEVICE in hotplug path

iommu/vt-d: Use BUS_NOTIFY_REMOVED_DEVICE in hotplug path

BugLink: http://bugs.launchpad.net/bugs/1555640
commit e6a8c9b337eed56eb481e1b4dd2180c25a1e5310 upstream.

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>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>