tee: optee: discover services dependent on tee-supplicant

Makes OP-TEE to enumerate also services depending on tee-supplicant
support in U-Boot. This change allows OP-TEE services like fTPM TA
to be discovered and get a TPM device registered in U-Boot.

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