dmaengine: add support to provide error result from a DMA transation

Adding a new callback that will provide the error result for a transaction.
The result is allocated on the stack and the callback should create a copy
if it wishes to retain the information after exiting. The result parameter
is now defined and takes over the dummy void pointer we placed in the
helper functions previously. dmaengine drivers should start converting
to the new "callback_result" callback in order to receive transaction
results.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>