fix the wrong file include in startup.c file

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@476 bbd45198-f89e-11dd-88c7-29a3b14d5316

bsp/lpc1766/startup.c

@@ -18,7 +18,6 @@
 
 #include "lpc17xx.h"
 #include "board.h"
-#include "rtc.h"
 
 /**
  * @addtogroup LPC17