dmaengine: edma: Simplify function parameter list for channel operations

Instead of passing a pointer to struct edma_cc and the channel number,
pass only the pointer to the edma_chan structure for the given channel.
This struct contains all the information needed by the functions and the
use of this makes it obvious that most of the sanity checks can be removed
from the driver.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>