gfio: fix tickmark shortening for zero special case

"0" tickmark can effectively be shortened by dividing by
any number as 0 / anything is still 0, but the code was
considering "0" to be unshortenable.

Signed-off-by: Stephen M. Cameron <stephenmcameron@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1 file changed