Fix code warning.

Change-Id: Ib11fb49f528d3688351ae349d5b4e307c28b3967
diff --git a/mbtk/mbtk_utils/mbtk_reboot.c b/mbtk/mbtk_utils/mbtk_reboot.c
index 3263d73..d839ae6 100755
--- a/mbtk/mbtk_utils/mbtk_reboot.c
+++ b/mbtk/mbtk_utils/mbtk_reboot.c
@@ -1,6 +1,8 @@
+#include <string.h>
 #include "mbtk_type.h"
 #include "mbtk_device.h"
-
+#include "mbtk_utils.h"
+#if 0
 static char* band_2_str(mbtk_modem_band_area_enum band_area)
 {
     switch(band_area)
@@ -13,6 +15,7 @@
             return "ALL";
     }
 }
+#endif
 
 static void help()
 {
@@ -22,7 +25,7 @@
 int main(int argc, char *argv[])
 {
     if(argc == 1) {
-        system("reboot -f");
+        mbtk_system("reboot -f");
     } else if(argc == 2) {
         if(strcmp(argv[1], "download")) {
             help();
@@ -48,8 +51,8 @@
         return -1;
     }
 
-    system("sync");
-    system("reboot -f");
+    mbtk_system("sync");
+    mbtk_system("reboot -f");
 
     return 0;
 }