x86: ptrace, bts: fix an unreachable statement

Commit c2724775 put a statement
after return, which makes that statement unreachable.

Move that statement before return.
Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Markus Metzger <markus.t.metzger@intel.com>
LKML-Reference: <20090313075622.GB8933@hack>
Cc: <stable@kernel.org> # .29 only
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/ptrace.c

@@ -685,9 +685,8 @@ static int ptrace_bts_config(struct task_struct *child,
 		if (!cfg.signal)
 			return -EINVAL;
 
-		return -EOPNOTSUPP;
-
 		child->thread.bts_ovfl_signal = cfg.signal;
+		return -EOPNOTSUPP;
 	}
 
 	if ((cfg.flags & PTRACE_BTS_O_ALLOC) &&