dmaengine: omap-dma: Do not suppress interrupts for memcpy

If the client queues up more transfers the driver will not able to move to
the next transfer without knowing that the previous descriptor is
completed.

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