minor fix in validate (#720)
minor fix in validate (#720)

I've noticed this make to create empty arrays and then appending
items. This will also result in 'unknown key' log if verbose
level is high enough.

Instead of creating cfgkey properly, this PR just removed it and
made classifyKeys iterate over the keys in the cfg map directly.

Former-commit-id: d32b987a482e3eac638dbdd93badf4bb82dee7b4
mandarjog/istio,frankbu/istio,smawson/istio,geeknoid/istio,geeknoid/istio,istio/istio,istio/istio,smawson/istio,sebastienvas/istio,sebastienvas/istio,frankbu/istio,istio/istio,frankbu/istio,geeknoid/istio,istio/istio,istio/istio,smawson/istio,frankbu/istio,smawson/istio,geeknoid/istio,sebastienvas/istio,smawson/istio,geeknoid/istio,sebastienvas/istio,mandarjog/istio,frankbu/istio,frankbu/istio,smawson/istio,mandarjog/istio,mandarjog/istio,mandarjog/istio,geeknoid/istio,sebastienvas/istio