tracing/fastboot: build fix

fix:

 In file included from kernel/sysctl.c:52:
 include/linux/ftrace.h:217: error: 'KSYM_NAME_LEN' undeclared here (not in a function)
Signed-off-by: NIngo Molnar <mingo@elte.hu>

include/linux/ftrace.h

 #ifndef _LINUX_FTRACE_H
 #define _LINUX_FTRACE_H
 
-#ifdef CONFIG_FTRACE
-
 #include <linux/linkage.h>
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/kallsyms.h>
 
+#ifdef CONFIG_FTRACE
+
 extern int ftrace_enabled;
 extern int
 ftrace_enable_sysctl(struct ctl_table *table, int write,