dmaengine: sun6i: Correct burst length field offsets for H3

For the H3, the burst lengths field offsets in the channel configuration
register differs from earlier SoC generations.

Using the A31 register macros actually configured the H3 controller
do to bursts of length 1 always, which although working leads to higher
bus utilisation.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>