dt-bindings: arm: firmware: tlm,trusted-foundations: Convert txt bindings to yaml

Convert Trusted Foundation binding to the YAML syntax.

Signed-off-by: David Heidelberg <david@ixit.cz>
Link: https://lore.kernel.org/r/20211022232100.137067-1-david@ixit.cz


Signed-off-by: Rob Herring <robh@kernel.org>