dmaengine: imx-dma: merge old dma-v1.c with imx-dma.c

It is mainly a simple merge changing the prefix of some
functions to fit the imx-dma namings.

As there are no users of the old dma-v1.c api we can safely
remove this file.

Signed-off-by: Javier Martin <javier.martin@vista-silicon.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>