SupplicantStateTracker: only update BatteryStats if primary

Multiple STAs updating supplicant state to BatteryStats
doesn't make sense as the expected order of events
can become jumbled.

Thus, only update BatteryStats for the
SupplicantStateTracker corresponding to the primary
STA.

Bug: 181693252
Test: atest FrameworksWifiTests
Change-Id: I3a21a8c3a0ac7dede1746dd935eefef8453bf39d
1 file changed