FROMLIST: iommu: Add support for the map_pages() callback

Since iommu_pgsize can calculate how many pages of the
same size can be mapped/unmapped before the next largest
page size boundary, add support for invoking an IOMMU
driver's map_pages() callback, if it provides one.

Bug: 178537788
Change-Id: Id2dfb0f882c3c2ae385781de1d8cec178532c3ce
Link: https://lore.kernel.org/linux-iommu/20210408171402.12607-1-isaacm@codeaurora.org/T/#t


Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
Suggested-by: Will Deacon <will@kernel.org>