ftrace: fix build failure

fix:

 kernel/trace/ftrace.c: In function 'ftrace_release':
 kernel/trace/ftrace.c:271: error: implicit declaration of function 'ftrace_release_hash'

release_hash is not needed without dftraced.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/trace/ftrace.c

@@ -267,8 +267,6 @@ void ftrace_release(void *start, unsigned long size)
 		}
 	}
 	spin_unlock(&ftrace_lock);
-
-	ftrace_release_hash(s, e);
 }
 
 static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)