Ensure automatic battery saver won't stick

Fixes: 80527470
Test: Manual tests:
Test 1: (make sure automatic BS won't stick)
- Set up automatic battery saver at N%
- Wait until the battery goes below N% -> Battery saver will turn on
- Turn off the device
- Charge it until the battery goes above N%
- Turn on the device
- Make sure battery saver is off.

Test 1: (make sure manual BS will stick)
- Make sure the battery level is above the automatic threshold
- Manually enable BS
- Reboot
- Make sure battery saver is on.

Change-Id: I677fd586f6b25d0200392941cac2d13b57fe10b3