dmaengine: pl330: Clear callback_result for re-used descs

The pl330 driver re-uses DMA descriptors rather than reallocating
them each time. At present, upon re-use the .callback member is
cleared, but .callback result is not. This causes problems where a
consuming driver sets the .callback_result for some submissions but
not for others, as eventually the function is invoked erronously.

Clear .callback_result along with .callback

Signed-off-by: Daniel Scally <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Vinod Koul <[email protected]>

Author: djrscally

drivers/dma/pl330.c

@@ -2588,6 +2588,7 @@ static struct dma_pl330_desc *pluck_desc(struct list_head *pool,
 
 		desc->status = PREP;
 		desc->txd.callback = NULL;
+		desc->txd.callback_result = NULL;
 	}
 
 	spin_unlock_irqrestore(lock, flags);