staging: comedi: remove duplicate pointer assignments in attach functions

Some board pointer are assigned twice via comedi_board() in the comedi low
level driver attach functions. Remove the duplicate assignment from the
variable definition where the pointer is not used anyway until assigned later
in the function when dev->board_ptr, that comedi_board() relies on, is setup
correctly.
Signed-off-by: Christian Engelmayer <cengelma@gmx.at>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/das1800.c

@@ -1479,7 +1479,7 @@ static int das1800_probe(struct comedi_device *dev)
 static int das1800_attach(struct comedi_device *dev,
 			  struct comedi_devconfig *it)
 {
-	const struct das1800_board *thisboard = comedi_board(dev);
+	const struct das1800_board *thisboard;
 	struct das1800_private *devpriv;
 	struct comedi_subdevice *s;
 	unsigned int irq = it->options[1];

drivers/staging/comedi/drivers/das800.c

@@ -683,7 +683,7 @@ static int das800_probe(struct comedi_device *dev)
 
 static int das800_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 {
-	const struct das800_board *thisboard = comedi_board(dev);
+	const struct das800_board *thisboard;
 	struct das800_private *devpriv;
 	struct comedi_subdevice *s;
 	unsigned int irq = it->options[1];

drivers/staging/comedi/drivers/dt2801.c

@@ -545,7 +545,7 @@ static int dt2801_dio_insn_config(struct comedi_device *dev,
 */
 static int dt2801_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 {
-	const struct dt2801_board *board = comedi_board(dev);
+	const struct dt2801_board *board;
 	struct dt2801_private *devpriv;
 	struct comedi_subdevice *s;
 	int board_code, type;

drivers/staging/comedi/drivers/ni_at_a2150.c

@@ -695,7 +695,7 @@ static int a2150_probe(struct comedi_device *dev)
 
 static int a2150_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 {
-	const struct a2150_board *thisboard = comedi_board(dev);
+	const struct a2150_board *thisboard;
 	struct a2150_private *devpriv;
 	struct comedi_subdevice *s;
 	unsigned int irq = it->options[1];