tee: add TEE_IOCTL_PARAM_ATTR_META

Adds TEE_IOCTL_PARAM_ATTR_META which can be used to indicate meta
parameters when communicating with user space. These meta parameters can
be used by supplicant support multiple parallel requests at a time.

Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>