ARM: davinci: Add dma_mask to eDMA devices

The upcoming change to merge the arch/arm/common/edma.c into
drivers/dma/edma.c will need this change when booting daVinci devices in
no DT mode.

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