Fix 5386408: Fix battery state information propagation in Lock Screen

This fixes a bug where Lock Screen would sometimes inappropriately show
"charged" if it took a while for Lock Screen to get an update on the
battery state.  It now starts with the state set to BATTERY_STATUS_UNKNOWN
so we properly update listeners when we finally get battery information
in handleBatteryUpdate().

Change-Id: I71018a233f38b2f897ff2e6592d7e310550fa016

Author: Jim Miller

policy/src/com/android/internal/policy/impl/KeyguardUpdateMonitor.java

@@ -218,7 +218,7 @@ public void onChange(boolean selfChange) {
 
         // take a guess to start
         mSimState = IccCard.State.READY;
-        mBatteryStatus = BATTERY_STATUS_FULL;
+        mBatteryStatus = BATTERY_STATUS_UNKNOWN;
         mBatteryLevel = 100;
 
         mTelephonyPlmn = getDefaultPlmn();