refactor UART RX with IRQ

flashloader/src/main.rs

@@ -180,7 +180,7 @@ mod app {
             &mut cx.device.sysconfig,
             &clocks,
         );
-        let (tx, mut rx, _) = uart0.split_with_irq();
+        let (tx, rx) = uart0.split();
 
         let verif_reporter = VerificationReportCreator::new(0).unwrap();
 
@@ -193,6 +193,7 @@ mod app {
         Mono::start(cx.core.SYST, clocks.sysclk().raw());
         CLOCKS.set(clocks).unwrap();
 
+        let mut rx = rx.to_rx_with_irq();
         let mut rx_context = IrqContextTimeoutOrMaxSize::new(MAX_TC_FRAME_SIZE);
         rx.read_fixed_len_or_timeout_based_using_irq(&mut rx_context)
             .expect("initiating UART RX failed");