dmaengine: omap-dma: Fix polled channel completion detection and handling

When based on the CCR_ENABLE bit the channel is stopped we should not call
omap_dma_callback(), only change the return value to DMA_COMPLETE. Client
drivers will do the right thing to clean up the channel after the transfer
has been completed.
Check the CCR_ENABLE only if the channel is running and not paused since
pause in sDMA means that the channel is stopped.
This will fix one hard to reproduce race condition when the channel is
terminated during transfer (affecting cyclic operation).

Fixes: 1a7cf7b2 ("dmaengine: omap-dma: Handle cases when the channel is polled for completion")

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