OMAPFB: fix compilation warnings due to missing include

Fix warnings similar to this by including module.h:

drivers/video/omap/dispc.c:276:1: warning: data definition has no type
or storage class
drivers/video/omap/dispc.c:276:1: warning: type defaults to 'int' in
declaration of 'EXPORT_SYMBOL'

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