Revert "staging: comedi: cb_pcidas64: change params to external_ai_queue_in_use()"

This reverts commit f5f3a2c6569e ("staging: comedi: cb_pcidas64: change
params to external_ai_queue_in_use()").  The
`external_ai_queue_in_use()` was being called from `ao_cmd()` with
pointers to the "write" subdevice and AO command, but is supposed to
check whether the external AI queue is currently in use by the "read"
subdevice and AI command.  In fact, the return value always indicated
that the external AI queue was not in use in this case (because the AO
command's channel list is sequential), so was fairly useless.  (However,
even before the reverted commit, the logic in
`external_ai_queue_in_use()` was wrong.  That will be corrected in a
subsequent commit.)

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/cb_pcidas64.c

@@ -3247,17 +3247,15 @@ static int prep_ao_dma(struct comedi_device *dev, const struct comedi_cmd *cmd)
 	return 0;
 }
 
-static inline int external_ai_queue_in_use(struct comedi_device *dev,
-					   struct comedi_subdevice *s,
-					   struct comedi_cmd *cmd)
+static inline int external_ai_queue_in_use(struct comedi_device *dev)
 {
 	const struct pcidas64_board *board = dev->board_ptr;
 
-	if (s->busy)
+	if (dev->read_subdev->busy)
 		return 0;
 	if (board->layout == LAYOUT_4020)
 		return 0;
-	else if (use_internal_queue_6xxx(cmd))
+	else if (use_internal_queue_6xxx(&dev->read_subdev->async->cmd))
 		return 0;
 	return 1;
 }
@@ -3291,7 +3289,7 @@ static int ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 	struct pcidas64_private *devpriv = dev->private;
 	struct comedi_cmd *cmd = &s->async->cmd;
 
-	if (external_ai_queue_in_use(dev, s, cmd)) {
+	if (external_ai_queue_in_use(dev)) {
 		warn_external_queue(dev);
 		return -EBUSY;
 	}