echo back UART input

let main run the main loop instead of the CDC ACM example.
also rename the CDC ACM example functions.

Change-Id: I44b15079672b4058de1fa08365541317d54958dc
diff --git a/sysmoOCTSIM/usb_start.h b/sysmoOCTSIM/usb_start.h
index 48b2735..daf30cc 100644
--- a/sysmoOCTSIM/usb_start.h
+++ b/sysmoOCTSIM/usb_start.h
@@ -15,7 +15,7 @@
 #include "cdcdf_acm.h"
 #include "cdcdf_acm_desc.h"
 
-void cdcd_acm_example(void);
+void usb_start(void);
 void cdc_device_acm_init(void);
 
 /**