V4L/DVB (6269): V4L: Fix a "scheduling while atomic" bug in saa7134

set_tvnorm can sleep in saa7134_i2c_xfer
(it will be called through tuner code)
but code calls it under spinlock. Fix that
Signed-off-by: NMaxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/saa7134/saa7134-video.c

@@ -1834,7 +1834,11 @@ static int video_do_ioctl(struct inode *inode, struct file *file,
 		if (res_check(fh, RESOURCE_OVERLAY)) {
 			spin_lock_irqsave(&dev->slock,flags);
 			stop_preview(dev,fh);
+			spin_unlock_irqrestore(&dev->slock, flags);
+
 			set_tvnorm(dev,&tvnorms[i]);
+
+			spin_lock_irqsave(&dev->slock, flags);
 			start_preview(dev,fh);
 			spin_unlock_irqrestore(&dev->slock,flags);
 		} else