compositor-fbdev: remove unused field 'depth'

Not referenced anywhere ever, has been there since the introduction of
fbdev-backend.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Ian Ray <ian.ray@ge.com>

libweston/compositor-fbdev.c

@@ -91,7 +91,6 @@ struct fbdev_output {
 
 	/* pixman details. */
 	pixman_image_t *hw_surface;
-	uint8_t depth;
 };
 
 static const char default_seat[] = "seat0";