staging: comedi: amplc_pci230: add a missing unlock

This side of the if else statement returned with the lock held and IRQs
disabled.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/amplc_pci230.c

@@ -1387,6 +1387,8 @@ static int pci230_ao_inttrig_scan_begin(struct comedi_device *dev,
 		/* Delay.  Should driver be responsible for this? */
 		/* XXX TODO: See if DAC busy bit can be used. */
 		udelay(8);
+	} else {
+		spin_unlock_irqrestore(&devpriv->ao_stop_spinlock, irqflags);
 	}
 
 	return 1;