Pull dma-mapping updates from Christoph Hellwig:
 "Very light this round as the interesting dma mapping changes went
  through the x86 tree.

  This just provides proper stubs for architectures not supporting dma
  (Geert Uytterhoeven)"

* tag 'dma-mapping-4.17' of git://git.infradead.org/users/hch/dma-mapping:
  usb: gadget: Add NO_DMA dummies for DMA mapping API
  scsi: Add NO_DMA dummies for SCSI DMA mapping API
  mm: Add NO_DMA dummies for DMA pool API
  dma-coherent: Add NO_DMA dummies for managed DMA API
  dma-mapping: Convert NO_DMA get_dma_ops() into a real dummy