Tools: fixed printf format errors

Tools/AP_Bootloader/support.h

@@ -46,7 +46,7 @@ void led_toggle(unsigned led);
 
 // printf to debug uart (or USB)
 extern "C" {
-void uprintf(const char *fmt, ...);
+void uprintf(const char *fmt, ...) FMT_PRINTF(1,2);
 }
 
 // generate a LED sequence forever

Tools/AP_Periph/AP_Periph.h

@@ -243,6 +243,6 @@ namespace AP
 extern AP_Periph_FW periph;
 
 extern "C" {
-void can_printf(const char *fmt, ...);
+void can_printf(const char *fmt, ...) FMT_PRINTF(1,2);
 }