staging: comedi: remove unnecessary dev->board_name initialization

The dev->board_name is now initialized by the comedi core before calling
the(*attach) or (*auto_attach) function in a driver. As long as the driver
does no additional probing, it's no longer necessary initialize the board_name.

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