Userspace PFNMAP buffers need to be mapped to the device like the
userspace non-PFNMAP buffers in order for the DMA mapping implementation
to create IOMMU mappings when we'll switch to the IOMMU-aware DMA
mapping backend.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>