core: pta: add Rockchip secure boot PTA

The S_OTP area for the Rockchip secure boot RSA hash and status register
is accessible only from the secure world. Thus, secure boot must be
enabled from the

core: pta: add Rockchip secure boot PTA

The S_OTP area for the Rockchip secure boot RSA hash and status register
is accessible only from the secure world. Thus, secure boot must be
enabled from the secure world on these board.

The PTA implements 3 functions:

1. Ask the TA from the non-secure world about the current status and hash
of the hardware. This allows to inspect the current status of secure
boot on a specific device.

2. Write an RSA hash into the OTP fuses. It's the responsibility of the
user to calculate the hash and ensure that it matches the key, which
will be used to sign the images.

3. Actually lockdown the device by enabling secure boot. This is a
separate step to allow the user to verify the setup before
potentially bricking a device.

With these functions, a user may use a client running in the normal
world (for example in a boot loader or operating system) to enable
secure boot on a Rockchip device.

Implementing secure boot setup as an OP-TEE PTA has the advantage that
secure boot can be enabled at any time during the device setup instead
of during early boot. This allows a developer/user or additional scripts
to interact with the secure boot setup process.

The hash of the root key is accepted and reported as calculated by
sha256sum and internally converted to the correct byte order that needs
to be burned into the fuses.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>

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