V4L/DVB (7121): Renames videobuf lock to vb_lock

This helps to identify where vb_lock is being used, and find missusages of the
locks.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/saa7134/saa7134-empress.c b/drivers/media/video/saa7134/saa7134-empress.c
index b1b01fa..94b81e1 100644
--- a/drivers/media/video/saa7134/saa7134-empress.c
+++ b/drivers/media/video/saa7134/saa7134-empress.c
@@ -87,7 +87,7 @@
 
 	dprintk("open minor=%d\n",minor);
 	err = -EBUSY;
-	if (!mutex_trylock(&dev->empress_tsq.lock))
+	if (!mutex_trylock(&dev->empress_tsq.vb_lock))
 		goto done;
 	if (dev->empress_users)
 		goto done_up;
@@ -101,7 +101,7 @@
 	err = 0;
 
 done_up:
-	mutex_unlock(&dev->empress_tsq.lock);
+	mutex_unlock(&dev->empress_tsq.vb_lock);
 done:
 	return err;
 }
@@ -110,7 +110,7 @@
 {
 	struct saa7134_dev *dev = file->private_data;
 
-	mutex_lock(&dev->empress_tsq.lock);
+	mutex_lock(&dev->empress_tsq.vb_lock);
 	videobuf_stop(&dev->empress_tsq);
 	videobuf_mmap_free(&dev->empress_tsq);
 	dev->empress_users--;
@@ -122,7 +122,7 @@
 	saa_writeb(SAA7134_AUDIO_MUTE_CTRL,
 		saa_readb(SAA7134_AUDIO_MUTE_CTRL) | (1 << 6));
 
-	mutex_unlock(&dev->empress_tsq.lock);
+	mutex_unlock(&dev->empress_tsq.vb_lock);
 	return 0;
 }