staging: comedi: dt2801: replace comedi_board() calls

The `comedi_board(dev)` inline function calls just return
`dev->board_ptr`.  Expand the inline function calls.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/dt2801.c

@@ -557,7 +557,7 @@ static int dt2801_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 
 havetype:
 	dev->board_ptr = boardtypes + type;
-	board = comedi_board(dev);
+	board = dev->board_ptr;
 
 	n_ai_chans = probe_number_of_ai_chans(dev);