drm/pagemap: Use dma-map IOVA alloc, link, and sync API for DRM pagemap

drm/pagemap: Use dma-map IOVA alloc, link, and sync API for DRM pagemap

The dma-map IOVA alloc, link, and sync APIs perform significantly better
than dma-map / dma-unmap, as they avoid costly IOMMU synchronizations.
This difference is especially noticeable when mapping a 2MB region in
4KB pages.

Use the IOVA alloc, link, and sync APIs for DRM pagemap, which create DMA
mappings between the CPU and GPU for copying data.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Francois Dugast <francois.dugast@intel.com>
Link: https://patch.msgid.link/20260410205929.3914474-5-matthew.brost@intel.com