dma-mapping: Add helpers for dma_range_map bounds

dma-mapping: Add helpers for dma_range_map bounds

Several places want to compute the lower and/or upper bounds of a
dma_range_map, so let's factor that out into reusable helpers.

Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com> # For arm64
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/45ec52f033ec4dfb364e23f48abaf787f612fa53.1713523152.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>