dmaengine: use DMA_COMPLETE for dma completion status

the DMA_SUCCESS is a misnomer as dmaengine indicates the transfer is complete and
gives no guarantee of the transfer success. Hence we should use DMA_COMPLTE
instead of DMA_SUCCESS

Acked-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>