media: v4l2-subdev: Add debug prints to v4l2_subdev_collect_streams()

Print streams found by v4l2_subdev_collect_streams() at debug level. This
could be useful in debugging drivers, userspace programs or the framework
itself.

Signed-off-by: Sakari Ailus <[e-mail]>
Reviewed-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/v4l2-core/v4l2-subdev.c

···
 		*found_streams = BIT_ULL(0);
 		*enabled_streams =
 			(sd->enabled_pads & BIT_ULL(pad)) ? BIT_ULL(0) : 0;
+		dev_dbg(sd->dev,
+			"collect_streams: sub-device \"%s\" does not support streams\n",
+			sd->entity.name);
 		return;
 	}
 
···
 		if (cfg->enabled)
 			*enabled_streams |= BIT_ULL(cfg->stream);
 	}
+
+	dev_dbg(sd->dev,
+		"collect_streams: \"%s\":%u: found %#llx enabled %#llx\n",
+		sd->entity.name, pad, *found_streams, *enabled_streams);
 }
 
 static void v4l2_subdev_set_streams_enabled(struct v4l2_subdev *sd,