[media] Revert "[media] tw5864: remove double irq lock code"

This reverts commit 617e901a ("[media] tw5864: remove double irq lock code").

That commit was rejected by Andrey Utkin <andrey_utkin@fastmail.com>,
but it had already been merged. Revert and apply Andrey's corrected
patch next.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/pci/tw5864/tw5864-core.c

@@ -157,10 +157,12 @@ static void tw5864_h264_isr(struct tw5864_dev *dev)
 
 		cur_frame = next_frame;
 
+		spin_lock_irqsave(&input->slock, flags);
 		input->frame_seqno++;
 		input->frame_gop_seqno++;
 		if (input->frame_gop_seqno >= input->gop)
 			input->frame_gop_seqno = 0;
+		spin_unlock_irqrestore(&input->slock, flags);
 	} else {
 		dev_err(&dev->pci->dev,
 			"Skipped frame on input %d because all buffers busy\n",