kernel: distro.config: enable 'BBR' TCP congestion algorithm

Coupled with the 'fq' qdisc it can do packet pacing to fight both bufferbloat and packet loss.

Signed-off-by: Koen Kooi <koen.kooi@linaro.org>
Signed-off-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>