Channel congestion score is not well bucketized, as we only have 0-25,
26-50, 51-75, 76-100, so small change will not give different score.
while channel congestion weight is high: 25.
Increase channel congestion slots num from 4 to 8 as following.
0-12% 13-25% 26-38% 39-50% 51-63% 64-75% 76-88% 87-100%
100% 90% 80% 70% 50% 25% 10% 5%
2500 2250 2000 1750 1250 625 250 125
Change-Id: I4fc2d8a5f0f64c5fce9fe5ec8f16c3e8e9665a60
CRs-Fixed: 2655110
a0cd009e7d