staging: comedi: cb_pcidas: fix a space before tab issue

As reported by checkpatch.pl, spaces should not be used before
tabs.
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>