Eruiklink curtain: use current_position to determine state

Description of situation_set seems to indicate that it should be the
reliable way to tell if the curtain is fully opened or fully closed, but
it does not seem to be the case.

Issue #1735

custom_components/tuya_local/devices/eruiklink_curtains.yaml

@@ -27,6 +27,9 @@ primary_entity:
     - id: 3
       type: integer
       name: current_position
+      range:
+        min: 0
+        max: 100
       mapping:
         - invert: true
     - id: 7
@@ -35,21 +38,20 @@ primary_entity:
       mapping:
         - dps_val: opening
           value: opening
-          constraint: situation_set
+          constraint: current_position
           conditions:
-            - dps_val: fully_open
+            - dps_val: 0
               value: opened
         - dps_val: closing
           value: closing
-          constraint: situation_set
+          constraint: current_position
           conditions:
-            - dps_val: fully_close
+            - dps_val: 100
               value: closed
     - id: 11
       type: string
       name: situation_set
       optional: true
-      persist: false
 secondary_entities:
   - entity: select
     name: Direction