dma-mapping: simplify the dma_sync_single_range_for_{cpu,device} implementation

We can just call the regular calls after adding offset the the address instead
of reimplementing them.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Tested-by: Jesper Dangaard Brouer <brouer@redhat.com>
Tested-by: Tony Luck <tony.luck@intel.com>