staging: comedi: amplc_pci230: fix the ai/ao cmd->start_arg use for TRIG_INT

This driver trivially validates the cmd->start_arg for all cmd->start_src values
to be 0. For TRIG_INT source, the cmd->start_arg is actually the valid trig_num
that is passed to the async (*inttrig) callback.

Refactor the (*inttrig) functions so that the cmd->start_arg is used to check the
trig_num instead of the open coded values.

For aesthetics, refactor the ai (*do_cmd) to remove some unnecessary {}.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/amplc_pci230.c

@@ -1427,7 +1427,9 @@ static int pci230_ao_inttrig_start(struct comedi_device *dev,
 				   struct comedi_subdevice *s,
 				   unsigned int trig_num)
 {
-	if (trig_num != 0)
+	struct comedi_cmd *cmd = &s->async->cmd;
+
+	if (trig_num != cmd->start_src)
 		return -EINVAL;
 
 	s->async->inttrig = NULL;
@@ -2146,7 +2148,9 @@ static int pci230_ai_inttrig_start(struct comedi_device *dev,
 				   struct comedi_subdevice *s,
 				   unsigned int trig_num)
 {
-	if (trig_num != 0)
+	struct comedi_cmd *cmd = &s->async->cmd;
+
+	if (trig_num != cmd->start_arg)
 		return -EINVAL;
 
 	s->async->inttrig = NULL;
@@ -2432,12 +2436,10 @@ static int pci230_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 		}
 	}
 
-	if (cmd->start_src == TRIG_INT) {
+	if (cmd->start_src == TRIG_INT)
 		s->async->inttrig = pci230_ai_inttrig_start;
-	} else {
-		/* TRIG_NOW */
+	else	/* TRIG_NOW */
 		pci230_ai_start(dev, s);
-	}
 
 	return 0;
 }