Fix battery tip app name is empty

- Top waste app is linux process not android process. Therefore
it doesn't contains application label. Fixed by return the process
name if packages label is empty.

Fixes: 146558570
Test: follow the steps:
1. adb shell settings put global battery_tip_constants test_low_battery_tip=true
2. Unplug usb. Go to Settings -> Battery, it should show an item
"Phone used more than usual"
3. Click "phone used more than usual" item, all the items should
have title and icon.

Change-Id: I85c232bc6a048b3104c4fce0fcec2b944e8ac1b4

src/com/android/settings/Utils.java

@@ -749,7 +749,7 @@ public final class Utils extends com.android.settingslib.Utils {
                     | PackageManager.MATCH_ANY_USER);
             return appInfo.loadLabel(context.getPackageManager());
         } catch (PackageManager.NameNotFoundException e) {
-            Log.w(TAG, "Unable to find info for package: " + packageName);
+            Log.e(TAG, "Unable to find info for package: " + packageName);
         }
         return null;
     }