Convert linaro,optee-tz to json schema format for better documentation
and error checks.

NOTE: This change does introduce a stricter naming convention for
optee nodes.
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20210426164008.20000-1-nm@ti.comSigned-off-by: Rob Herring <robh@kernel.org>