media: v4l2-subdev: Print early in v4l2_subdev_{enable,disable}_streams()

Print debug messages early in v4l2_subdev_enable_streams() and
v4l2_subdev_disable_streams(), before sanity checks take place. This can
help figuring out why something goes wrong, in driver development or
otherwise.

Also print the name of the sub-device where streaming is to be enabled or
disabled.

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

···
 	bool use_s_stream;
 	int ret;
 
+	dev_dbg(dev, "enable streams \"%s\":%u/%#llx\n", sd->entity.name, pad,
+		streams_mask);
+
 	/* A few basic sanity checks first. */
 	if (pad >= sd->entity.num_pads)
 		return -EINVAL;
···
 		ret = -EALREADY;
 		goto done;
 	}
-
-	dev_dbg(dev, "enable streams %u:%#llx\n", pad, streams_mask);
 
 	already_streaming = v4l2_subdev_is_streaming(sd);
 
···
 	bool use_s_stream;
 	int ret;
 
+	dev_dbg(dev, "disable streams \"%s\":%u/%#llx\n", sd->entity.name, pad,
+		streams_mask);
+
 	/* A few basic sanity checks first. */
 	if (pad >= sd->entity.num_pads)
 		return -EINVAL;
···
 		ret = -EALREADY;
 		goto done;
 	}
-
-	dev_dbg(dev, "disable streams %u:%#llx\n", pad, streams_mask);
 
 	if (!use_s_stream) {
 		/* Call the .disable_streams() operation. */