ARM/dmaengine: edma: Merge the two drivers under drivers/dma/

Move the code out from arch/arm/common and merge it inside of the dmaengine
driver.
This change is done with as minimal (if eny) functional change to the code
as possible to avoid introducing regression.

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