staging: comedi: ni_daq_dio24: remove thisboard macro

The 'thisboard' macro relies on a local variable having a specific
name and yields a pointer derived from that local variable.

Replace the macro with a local variable and use the comedi_board()
helper to get the pointer.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/ni_daq_dio24.c

@@ -83,18 +83,14 @@ static const struct dio24_board_struct dio24_boards[] = {
 	 },
 };
 
-/*
- * Useful for shorthand access to the particular board structure
- */
-#define thisboard ((const struct dio24_board_struct *)dev->board_ptr)
-
 struct dio24_private {
 
 	int data;		/* number of data points left to be taken */
 };
 
 static int dio24_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 {
+	const struct dio24_board_struct *thisboard = comedi_board(dev);
 	struct dio24_private *devpriv;
 	struct comedi_subdevice *s;
 	unsigned long iobase = 0;
@@ -159,6 +155,7 @@ static int dio24_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 
 static void dio24_detach(struct comedi_device *dev)
 {
+	const struct dio24_board_struct *thisboard = comedi_board(dev);
 	struct comedi_subdevice *s;
 
 	if (dev->subdevices) {