cdc_uart: add missing clear-break reset of TX LED

src/cdc_uart.c

diff --git a/src/cdc_uart.c b/src/cdc_uart.c
index 6f2450a..6dc6534 100644
--- a/src/cdc_uart.c
+++ b/src/cdc_uart.c
@@ -278,6 +278,9 @@
     case 0:
     uart_set_break(PROBE_UART_INTERFACE, false);
     timed_break = false;
+#ifdef PROBE_UART_TX_LED
+    tx_led_debounce = 0;
+#endif
     break;
     case 0xffff:
     uart_set_break(PROBE_UART_INTERFACE, true);