linux-phytec-fsl

Documentation: dmaengine: Update the documentation

Now that we have splitted device_control and removed device_slave_caps in favor
of a few dma_device variables, update the documentation accordingly.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>