xfs/442: rescale load so it's not exponential

xfs/442: rescale load so it's not exponential

....
xfs/442 491
....

xfs/442 takes a long time to run because it is scaling the load
by the number of processes it is going to run on twice. It scales
the number of operations by the number of processes it is going to
run, meaning that doubling the number of processes quadruples the
runtime.

Reduce it to scale linearly by fixing the number of ops it runs per
process.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Zorro lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>