ARM: dts: omap5: add address-cells & size-cells to dsi

Add address-cells & size-cells to DSI nodes so that board files do not
need to define them.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201215104657.802264-58-tomi.valkeinen@ti.com