Downgrade the log level of exception log

This exception log is usually printed when the device connects to
a wifi. The cause is that when the device connects to a wifi,
wifi will send CONNECTING state first, then CONNECTED state.
And in CONNECTING state, wifi will send the LinkProperties to
ConnectivityService and ConnectivityService will try to update
that LinkProperties(including interface) to netd. But the netid
hasn't set to netd yet before wifi CONNECTED, so this exception
log will be printed.
There is no really issue in this case, so downgrade the log level
might be a better thing for all Android developer.

Bug: 181269159
Test: m
Change-Id: I61c09352225a610fcd6d3dd33b782ee114c35fc5