OMAPDSS: omapdss.h: add owner field to omap_dss_device

Add struct module *owner field to omap_dss_device, which points to the
module containing the ops for this omap_dss_device. This will be used to
manage the ref count for the module.

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