Merge tag 'dma-mapping-4.20-2' of git://git.infradead.org/users/hch/dma-mapping

Pull dma-mapping fix from Christoph Hellwig:
 "Avoid compile warnings on non-default arm64 configs"

* tag 'dma-mapping-4.20-2' of git://git.infradead.org/users/hch/dma-mapping:
  arm64: fix warnings without CONFIG_IOMMU_DMA