Vevor EV charger: improve compatibility with US model

Many dps are optional, probably also for the EU model, depending on the
current settings of the device.

Issue #1757

custom_components/tuya_local/devices/vevor_ev_charger.yaml

@@ -165,6 +165,7 @@ secondary_entities:
     dps:
       - id: 14
         type: string
+        optional: true
         name: option
         mapping:
           - dps_val: charge_now
@@ -206,6 +207,7 @@ secondary_entities:
     dps:
       - id: 25
         type: integer
+        optional: true
         name: sensor
         unit: kWh
         mapping:
@@ -230,6 +232,7 @@ secondary_entities:
     dps:
       - id: 28
         type: integer
+        optional: true
         name: value
         unit: h
         range: