Fix battery page crashing when there is no battery

Author: Steve-Tech

yafi/battery.py

@@ -50,6 +50,9 @@ def __init__(self, **kwargs):
 
     def setup(self, app):
         battery = ec_commands.memmap.get_battery_values(app.cros_ec)
+        if not battery:
+            self.batt_status.set_subtitle("No data")
+            return
         self.batt_manu.set_subtitle(battery["manufacturer"])
         self.batt_model.set_subtitle(battery["model"])
         self.batt_serial.set_subtitle(battery["serial"])