fixed invalid assignment of 64bit mask to host dma_boundary for scatter gather segment boundary limit.

commit f76a610a upstream.

In reference to bug https://bugzilla.redhat.com/show_bug.cgi?id=1097141
Assert is seen with AMD cpu whenever calling pci_alloc_consistent.

[   29.406183] ------------[ cut here ]------------
[   29.410505] kernel BUG at lib/iommu-helper.c:13!
Signed-off-by: Minh Tran <minh.tran@emulex.com>
Fixes: 6733b39aSigned-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>