For memcpy we never stored the start address of the transfer for the pset
which rendered the memcpy residue calculation completely broken.

In the edma_residue() function we also need to to some correction for the
calculations:
Instead waiting for all EDMA channels to be idle (in a busy system it can
take few iteration to hit a point when all queues are idle) wait for the
event pending on the given channel (SH_ER for hw synchronized channels,
SH_ESR for manually triggered channels).

If the position returned by EMDA is 0 it implies that the last paRAM set
has been consumed and we are at the closing dummy set, thus we can conclude
that the transfer is completed and we can return 0 as residue.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
[vkoul: fixed typo in commit log]
Link: https://lore.kernel.org/r/20190716082655.1620-3-peter.ujfalusi@ti.comSigned-off-by: Vinod Koul <vkoul@kernel.org>