Loratap double curtain switch: use class consistent with name

Classes were inconsistent. Noticed in review of derived PR #2958

custom_components/tuya_local/devices/loratap_wifi_curtain_switch_double.yaml

@@ -6,7 +6,7 @@ products:
 entities:
   - entity: cover
     name: Curtain 1
-    class: blind
+    class: curtain
     dps:
       - id: 1
         name: control
@@ -29,6 +29,7 @@ entities:
         type: integer
   - entity: cover
     name: Curtain 2
+    class: curtain
     dps:
       - id: 4
         name: control