Staging: comedi: fix line over 80 character warning in unioxx5.c

This is a patch to unioxx5.c that fixes the line over 80 character
warning found by checkpatch.pl by initializing n_subd before the
for loop

Signed-off-by: Conrad Gomes <conrad.s.j.gomes@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>