dmaengine: ti: omap-dma: Improved memcpy polling support

dmaengine: ti: omap-dma: Improved memcpy polling support

When a DMA client driver does not set the DMA_PREP_INTERRUPT because it
does not want to use interrupts for DMA completion or because it can not
rely on DMA interrupts due to executing the memcpy when interrupts are
disabled it will poll the status of the transfer.

If the interrupts are enabled then the cookie will be set completed in the
interrupt handler so only check in HW completion when the polling is really
needed.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20190716082459.1222-3-peter.ujfalusi@ti.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>