[media] v4l: soc-camera: fix multiple simultaneous user case

A recent patch has introduced a regression, whereby a second open of an
soc-camera video device breaks the running capture. This patch fixes this bug
by guaranteeing, that video buffers get initialised only during the first open
of the device node.

Signed-off-by: Guennadi Liakhovetski <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/video/soc_camera.c

···
 		ret = soc_camera_set_fmt(icd, &f);
 		if (ret < 0)
 			goto esfmt;
+
+		ici->ops->init_videobuf(&icd->vb_vidq, icd);
 	}
 
 	file->private_data = icd;
 	dev_dbg(&icd->dev, "camera device open\n");
-
-	ici->ops->init_videobuf(&icd->vb_vidq, icd);
 
 	mutex_unlock(&icd->video_lock);