Remove plug/unplug condition for the incompatible charging

Remove the plug/unplug condition checking for the incompatible
notification based on the feedback from:
https://b.corp.google.com/issues/276403405#comment3

Bug: 276403405
Test: make -j64 RunSettingsRoboTests ROBOTEST_FILTER="com.android.settings.fuelgauge.batterytip"
Change-Id: Iec177ed33a3cc8cf5a5747b6f65440d31120823c