iommu/rockchip: Remove redundant DMA syncs

When we allocate new pagetable pages, we don't modify them between the
initial dma_map_single() call and the dma_sync_single_for_device() call
via rk_iommu_flush(), so the latter is entirely pointless.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/5c29a9ff0a20df0167635b1901f94b5195c1fb28.1621604979.git.robin.murphy@arm.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>