Switch SERCOM7 (Debug UART) to sync mode + add STDIO

this will allow us to do printf()

Change-Id: Ibf4ba961d4bbf8d787558f38f3d557422587aad3
diff --git a/sysmoOCTSIM/atmel_start.h b/sysmoOCTSIM/atmel_start.h
index 953f947..92afa47 100644
--- a/sysmoOCTSIM/atmel_start.h
+++ b/sysmoOCTSIM/atmel_start.h
@@ -7,6 +7,7 @@
 
 #include "driver_init.h"
 #include "usb_start.h"
+#include "stdio_start.h"
 
 /**
  * Initializes MCU, drivers and middleware in the project