media: v4l: omap_vout: vrfb: Use the wrapper for prep_interleaved_dma()

Instead of directly accessing to dmadev->device_prep_interleaved_dma() use
the dmaengine_prep_interleaved_dma() wrapper instead.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>