netfilter: xt_rateest: fix u64 truncation in xt_rateest_mt()

netfilter: xt_rateest: fix u64 truncation in xt_rateest_mt()

On links faster than ~34 Gbps, where byte rate may exceed 2^32-1
(~ 4.3 GBps), the comparison result becomes incorrect because the
truncated value no longer reflects the actual estimator rate.

Fix by changing the local variables to u64.

Fixes: 1c0d32fde5bd ("net_sched: gen_estimator: complete rewrite of rate estimators")
Signed-off-by: Feng Wu <wufengwufengwufeng@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>