ARM: at91/dt: ov2640: add hsync/vsync-active property

On at91sam9x5ek/at91sam9m10g45ek/sama5d3xek boards, we use the parallel
connection for ov2640. So we must set the hsync/vsync property (1 means
active high).
Otherwise, the connection would be seen as BT.656 or BT.1120.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>