Merge tag 'dma-mapping-4.18-2' of git://git.infradead.org/users/hch/dma-mapping

Pull dma mapping fixlet from Christoph Hellwig:
 "Add a missing export required by riscv and unicore"

* tag 'dma-mapping-4.18-2' of git://git.infradead.org/users/hch/dma-mapping:
  swiotlb: export swiotlb_dma_ops