refactor: use crate::util::mk_static in mqtt module

rust/src/mqtt.rs

@@ -110,14 +110,7 @@ async fn publish_inner(subtopic: &str, message: &str) -> FatResult<()> {
     }
 }
 
-macro_rules! mk_static {
+use crate::util::mk_static;
-    ($t:ty,$val:expr) => {{
-        static STATIC_CELL: static_cell::StaticCell<$t> = static_cell::StaticCell::new();
-        #[deny(unused_attributes)]
-        let x = STATIC_CELL.uninit().write(($val));
-        x
-    }};
-}
 
 pub async fn mqtt_init(
     network_config: &'static NetworkConfig,