Documentation: dt: Add Allwinner A31 DMA controller bindings

The Allwinner A31 DMA controller is rather simple to describe in the DT. Add
the bindings documentation.

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