csky: Fix a size determination in gpr_get()

"*" is missed  in size determination as we are passing register set
rather than a pointer.

Fixes: dcad7854fc ("sky: switch to ->regset_get()")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@gmail.com>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

arch/csky/kernel/ptrace.c

@@ -84,7 +84,7 @@ static int gpr_get(struct task_struct *target,
 	/* Abiv1 regs->tls is fake and we need sync here. */
 	regs->tls = task_thread_info(target)->tp_value;
 
-	return membuf_write(&to, regs, sizeof(regs));
+	return membuf_write(&to, regs, sizeof(*regs));
 }
 
 static int gpr_set(struct task_struct *target,