rockchip: Support OP-TEE for ARM in FIT images created by binman

CONFIG_SPL_OPTEE_IMAGE option is used during DRAM size detection for
Rockchip ARM platform to indicate that an OP-TEE binary was already loaded
and a Trusted Execution Environment (TEE) is available in order to
block/reserve a memory-region for it.

This adds a bunch of new `#if's` to u-boot-rockchip.dtsi to include the
OP-TEE binary in the FIT image for ARM SOCs if CONFIG_SPL_OPTEE_IMAGE is
selected.
That makes it a little harder to read, but I opted for that, because all
the duplicates in an extra ARM-OP-TEE-specfic .dtsi would be the greater
evil, IMHO. Besides it's more likley being "forgotten" to sync when changes
in u-boot-rockchip.dtsi are made.

The no longer required rockchip-optee.dtsi and it's inclusions are dropped.

The hardcoded load address is common across all OP-TEE implemenations for
Rockchip (vendor and upstream).

The OP-TEE-binary is non-optional if CONFIG_SPL_OPTEE_IMAGE is selected and
there will be an error if the file does not exist and/or `TEE=` build
option is missing.

Signed-off-by: Alex Bee <knaerzche@gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>