dmaengine: edma: Add channel number to debug prints

It helps to identify issues if we have some information regarding to the
channel which the event is associated.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Joel Fernandes <joelf@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>