Pull dma-mapping helpers from Christoph Hellwig:
 "These were in a separate stable branch so that various media and drm
  trees could pull the in for bug fixes, but looking at linux-next that
  hasn't actually happened yet. Still sending the APIs to you in the
  hope that these bug fixes get picked up for 5.8 in one way or another.

  Summary:

   - add DMA mapping helpers for struct sg_table (Marek Szyprowski)"

* tag 'dma-mapping-5.8-2' of git://git.infradead.org/users/hch/dma-mapping:
  iommu: add generic helper for mapping sgtable objects
  scatterlist: add generic wrappers for iterating over sgtable objects
  dma-mapping: add generic helpers for mapping sgtable objects