staging: comedi: adl_pci6208: cleanup pci6208_attach()

For aesthetic reasons, set the dev->board_name as soon as the
thisboard pointer is available.

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>