Ignore the first modem activity when system_server start

Don't count up the first reported modem activity as the
modem power stats updates to battery stats.

Bug: 283337636
Test: atest BatteryStatsNoteTest MobileRadioPowerCalculatorTest
Change-Id: I5894eb70b9b014bea831b5ea3d00e5405eae59ac
(cherry picked from commit 0870ea92175d2509ab19a23595efdb5f55c36dfc)
3 files changed