ARM: dts: pl330: Add #dma-cells for generic dma binding support

This patch adds #dma-cells property to PL330 DMA controller
nodes for supporting generic dma dt bindings on samsung
exynos5250 platform.

Signed-off-by: Padmavathi Venna <padma.v@samsung.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>