sniff mode: handle USART 1 RX interrupt to show sniffer data

Change-Id: I5504369aed39844b7cf21e5b3ccb542daa6b946e

firmware/apps/trace/main.c

@@ -36,6 +36,7 @@ static const conf_func config_func_ptrs[] = {
 		.init = Sniffer_init,
 		.exit = Sniffer_exit,
 		.run = Sniffer_run,
+		.usart1_irq = Sniffer_usart1_irq,
 	},
 #endif
 #ifdef HAVE_CCID