UART_debug now uses the async library with tx ring

Change-Id: I4cf689a8d3dc292201f1e2ce6c013aa1686ad6bc
diff --git a/sysmoOCTSIM/command.c b/sysmoOCTSIM/command.c
index 6fa25cf..454cd2f 100644
--- a/sysmoOCTSIM/command.c
+++ b/sysmoOCTSIM/command.c
@@ -81,7 +81,7 @@
 	unsigned int i = 0;
 
 	/* yield CPU after maximum of 10 received characters */
-	while (usart_async_is_rx_not_empty(&UART_debug) && (i < 10)) {
+	while (usart_async_rings_is_rx_not_empty(&UART_debug) && (i < 10)) {
 		int c = getchar();
 		if (c < 0)
 			return;