DMA: PL330: Remove the start operation for handling DMA_TERMINATE_ALL command

Original code carries out the start operation after flush operation.
But start operation is not required for DMA_TERMINATE_ALL command.
So, this patch removes the unnecessary start operation and only carries out
the flush operation for handling DMA_TERMINATE_ALL command.

Signed-off-by: Boojin Kim <boojin.kim@samsung.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
[Fixed typos in changelog]
Signed-off-by: Vinod Koul <vinod.koul@intel.com>