tee: optee: fix error return code in probe function

If teedev_open() fails, probe function need return
error code.

Fixes: aceeafef ("optee: use driver internal tee_context for some rpc")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>