iommu: fix MAX_ORDER usage in __iommu_dma_alloc_pages() MAX_ORDER is not inclusive: the maximum allocation order buddy allocator can deliver is MAX_ORDER-1. Fix MAX_ORDER usage in __iommu_dma_alloc_pages(). Also use GENMASK() instead of hard to read "(2U << order) - 1" magic. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Kirill A. Shutemov <[email protected]> Acked-by: Robin Murphy <[email protected]> Reviewed-by: Jacob Pan <[email protected]> Acked-by: Joerg Roedel <[email protected]> Signed-off-by: Andrew Morton <[email protected]>