tc/m_estimator: Print proper value for estimator interval in raw.

tc/m_estimator: Print proper value for estimator interval in raw.

While looking at the estimator code, I noticed an incorrect interval
number printed in raw for the handles. This patch fixes the formatting.

Before patch:

root@bytecenter.fr:~# tc -r filter add dev eth0 ingress estimator
250ms 999ms matchall action police avrate 12mbit conform-exceed drop
[estimator i=4294967294 e=2]

After patch:

root@bytecenter.fr:~# tc -r filter add dev eth0 ingress estimator
250ms 999ms matchall action police avrate 12mbit conform-exceed drop
[estimator i=-2 e=2]

Signed-off-by: Jamie Gloudon <jamie.gloudon@gmx.fr>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>