Use shorthand attributes for DLNA dmr (#99236)

homeassistant/components/dlna_dmr/media_player.py

@@ -129,6 +129,9 @@ class DlnaDmrEntity(MediaPlayerEntity):
     # determine whether further device polling is required.
     _attr_should_poll = True
 
+    # Name of the current sound mode, not supported by DLNA
+    _attr_sound_mode = None
+
     def __init__(
         self,
         udn: str,
@@ -745,11 +748,6 @@ class DlnaDmrEntity(MediaPlayerEntity):
             "Couldn't find a suitable mode for shuffle=%s, repeat=%s", shuffle, repeat
         )
 
-    @property
-    def sound_mode(self) -> str | None:
-        """Name of the current sound mode, not supported by DLNA."""
-        return None
-
     @property
     def sound_mode_list(self) -> list[str] | None:
         """List of available sound modes."""