staging: comedi: ni_daq_700: Remove bustype variable from the boardinfo

This driver is only used for pcmcia type devices. There is no need for
the 'bustype' check. Remove the variable from the boardinfo and refactor
the code based on it's removal.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Frank Mori Hess <fmhess@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>