Breville purifiers: correct day sensors

Day units is "d".  Do not use duration class, as that only shows
hhhh:mm:ss, and days is more relatable.

custom_components/tuya_local/devices/breville_easyair_purifier.yaml

@@ -44,7 +44,6 @@ secondary_entities:
   - entity: sensor
     name: Filter days left
     category: diagnostic
-    class: duration
     icon: "mdi:air-filter"
     dps:
       - id: 16

custom_components/tuya_local/devices/breville_smartairconnect_purifier.yaml

@@ -65,7 +65,7 @@ secondary_entities:
       - id: 16
         name: sensor
         type: integer
-        unit: day
+        unit: d
   - entity: select
     name: Timer
     icon: "mdi:fan-clock"