wifi: Remove logging duration from idle and active time calculation.

Wifi link layer stats aggregate the stats from multiple radios.
So on wifi chips with multiple radio support, active time and idle time
can go beyond logging duration(mainly in concurrent operation like
wifi sta + wifi tethering mode on). With this approach we can longer
assume that wifi activity time or idle time cannot go beyond the
logging duration. So removed the logging duration parameter in
computing the final idle time.

Bug: 36176141
Test: Manual - Verified the aggregation logic by logging the stats

Change-Id: I620047fb4ee363484c3d1d8e775bb6e582c1886a