tee: optee: Add SMC for loading OP-TEE image

Adds an SMC call that will pass an OP-TEE binary image to EL3 and
instruct it to load it as the BL32 payload. This works in conjunction
with a feature added to Trusted Firmware for ARMv8 and above
architectures that supports this.

The main purpose of this change is to facilitate updating the OP-TEE
component on devices via a rootfs change rather than having to do a
firmware update. Further details are linked to in the Kconfig file.

Signed-off-by: Jeffrey Kardatzke <jkardatzke@chromium.org>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jeffrey Kardatzke <jkardatzke@google.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>