rtmutex: Remove unused argument from rt_mutex_proxy_unlock()

stable inclusion
from linux-4.19.172
commit 29013e4f4b73e2f5ef39a443b05c231ac29c690f
CVE: CVE-2021-3347

--------------------------------

commit 2156ac19 upstream

Nothing uses the argument. Remove it as preparation to use
pi_state_update_owner().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>