Goodcell EV charger: make alt charge current optional

Based on #2102 (for Feyree Fey123), which almost matches except for this
dp. Likely this is only reported when in the mode it is used.

custom_components/tuya_local/devices/goodcell_ev_charger.yaml

@@ -121,6 +121,7 @@ secondary_entities:
                   max: 16
       - id: 114
         type: integer
+        optional: true
         name: value_alt
         unit: A
         range: