Fix camera state and attributes for agent_dvr (#54049)

* Fix camera state and attributes for agent_dvr

* tweak

* tweak

homeassistant/components/agent_dvr/camera.py

@@ -67,8 +67,6 @@ async def async_setup_entry(
 class AgentCamera(MjpegCamera):
     """Representation of an Agent Device Stream."""
 
-    _attr_supported_features = SUPPORT_ON_OFF
-
     def __init__(self, device):
         """Initialize as a subclass of MjpegCamera."""
         device_info = {
@@ -80,7 +78,6 @@ class AgentCamera(MjpegCamera):
         self._removed = False
         self._attr_name = f"{device.client.name} {device.name}"
         self._attr_unique_id = f"{device._client.unique}_{device.typeID}_{device.id}"
-        self._attr_should_poll = True
         super().__init__(device_info)
         self._attr_device_info = {
             "identifiers": {(AGENT_DOMAIN, self.unique_id)},
@@ -102,10 +99,10 @@ class AgentCamera(MjpegCamera):
             if self.device.client.is_available and not self._removed:
                 _LOGGER.error("%s lost", self.name)
                 self._removed = True
-        self._attr_available = self.device.client.is_available
         self._attr_icon = "mdi:camcorder-off"
         if self.is_on:
             self._attr_icon = "mdi:camcorder"
+        self._attr_available = self.device.client.is_available
         self._attr_extra_state_attributes = {
             ATTR_ATTRIBUTION: ATTRIBUTION,
             "editable": False,
@@ -117,6 +114,11 @@ class AgentCamera(MjpegCamera):
             "alerts_enabled": self.device.alerts_active,
         }
 
+    @property
+    def should_poll(self) -> bool:
+        """Update the state periodically."""
+        return True
+
     @property
     def is_recording(self) -> bool:
         """Return whether the monitor is recording."""
@@ -137,6 +139,11 @@ class AgentCamera(MjpegCamera):
         """Return True if entity is connected."""
         return self.device.connected
 
+    @property
+    def supported_features(self) -> int:
+        """Return supported features."""
+        return SUPPORT_ON_OFF
+
     @property
     def is_on(self) -> bool:
         """Return true if on."""