dt-bindings: arm: ti: Convert K3 board/soc bindings to DT schema

Convert TI K3 Board/SoC bindings to DT schema format.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Suman Anna <s-anna@ti.com>
Link: https://lore.kernel.org/r/20200914162231.2535-3-lokeshvutla@ti.com