[libc] Remove wrong include file in clock_time.c

components/libc/time/clock_time.c

@@ -24,12 +24,11 @@
  */
 
 #include <rtthread.h>
-#include <rtdevice.h>
 #include <pthread.h>
 
 #include "clock_time.h"
 
-struct timeval _timevalue;
+static struct timeval _timevalue;
 int clock_time_system_init()
 {
     time_t time;