The doxygen '\todo' directory doesn't need to be followed by a colon,
yet a few strayed occurrences have made their way in. Fix them.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>