[media] mt9m111: fix Oops - initialise context before dereferencing

A recent commit "[media] soc-camera: Push probe-time power management to
drivers" causes an Oops during mt9m111 driver probing because its .ctx
private data field is now dereferenced before it is initialised. Fix this
by initialising the field earlier.
Reported-by: NJavier Martin <javier.martin@vista-silicon.com>
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Tested-by: NJavier Martin <javier.martin@vista-silicon.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/i2c/soc_camera/mt9m111.c

@@ -785,8 +785,6 @@ static int mt9m111_init(struct mt9m111 *mt9m111)
 	struct i2c_client *client = v4l2_get_subdevdata(&mt9m111->subdev);
 	int ret;
 
-	/* Default HIGHPOWER context */
-	mt9m111->ctx = &context_b;
 	ret = mt9m111_enable(mt9m111);
 	if (!ret)
 		ret = mt9m111_reset(mt9m111);
@@ -975,6 +973,9 @@ static int mt9m111_probe(struct i2c_client *client,
 	if (!mt9m111)
 		return -ENOMEM;
 
+	/* Default HIGHPOWER context */
+	mt9m111->ctx = &context_b;
+
 	v4l2_i2c_subdev_init(&mt9m111->subdev, client, &mt9m111_subdev_ops);
 	v4l2_ctrl_handler_init(&mt9m111->hdl, 5);
 	v4l2_ctrl_new_std(&mt9m111->hdl, &mt9m111_ctrl_ops,