st_tty_open do not need local variable to store different value,
Hence just remove it.
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Link: https://lore.kernel.org/r/1568307147-43468-1-git-send-email-zhongjiang@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>