OMAP: DSS2: DSI: Add extra omap_dss_device argument in functions exported by dsi

Add pointer to omap_dss_device struct as an argument in the functions which
are exported to dsi panel drivers. This argument will tell the DSI driver
which DSI interface's data it has to choose.

Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>