Limiting the dma mask to avoid PCI (pre-PCIe) DAC cycles while paying
the huge overhead of an IOMMU is rather pointless, and this seriously
gets in the way of dma mapping work.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>