media: subdev: Add debug prints to enable/disable_streams

It is often useful to see when streaming for a device is being enabled
or disabled. Add debug prints for this to v4l2_subdev_enable_streams()
and v4l2_subdev_disable_streams().

Signed-off-by: Tomi Valkeinen <[e-mail]>
Reviewed-by: Jacopo Mondi <[e-mail]>
Signed-off-by: Sakari Ailus <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

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

···
 		goto done;
 	}
 
+	dev_dbg(dev, "enable streams %u:%#llx\n", pad, streams_mask);
+
 	/* Call the .enable_streams() operation. */
 	ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
 			       streams_mask);
-	if (ret)
+	if (ret) {
+		dev_dbg(dev, "enable streams %u:%#llx failed: %d\n", pad,
+			streams_mask, ret);
 		goto done;
+	}
 
 	/* Mark the streams as enabled. */
 	for (i = 0; i < state->stream_configs.num_configs; ++i) {
···
 		goto done;
 	}
 
+	dev_dbg(dev, "disable streams %u:%#llx\n", pad, streams_mask);
+
 	/* Call the .disable_streams() operation. */
 	ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
 			       streams_mask);
-	if (ret)
+	if (ret) {
+		dev_dbg(dev, "disable streams %u:%#llx failed: %d\n", pad,
+			streams_mask, ret);
 		goto done;
+	}
 
 	/* Mark the streams as disabled. */
 	for (i = 0; i < state->stream_configs.num_configs; ++i) {