iommu/amd: Remove PD_DMA_OPS_MASK

This is covered by IOMMU_DOMAIN_DMA from the IOMMU core code already,
so remove it.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Link: https://lore.kernel.org/r/20200527115313.7426-8-joro@8bytes.org