Fix implicit declaration of function 'htons'

Include <netinet/in.h> instead of <linux/in.h> to get htons()
prototpye.
Signed-off-by: NWolfgang Denk <wd@denx.de>

tools/ncb.c

 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/socket.h>
-#include <linux/in.h>
+#include <netinet/in.h>
 
 int main (int argc, char *argv[])
 {