staging: comedi: introduce 'comedi_board' helper function

This helper function is used to fetch the comedi_device board_ptr
which is used during the attach to pass board specific information
to the comedi drivers.
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/comedidev.h

@@ -235,6 +235,11 @@ struct comedi_device {
 	void (*close) (struct comedi_device *dev);
 };
 
+static inline const void *comedi_board(struct comedi_device *dev)
+{
+	return dev->board_ptr;
+}
+
 struct comedi_device_file_info {
 	struct comedi_device *device;
 	struct comedi_subdevice *read_subdevice;