Convert the old device tree documentation to yaml format.

Signed-off-by: Lucas Oshiro <lucasseikioshiro@gmail.com>
Signed-off-by: Rodrigo Ribeiro <rodrigorsdc@gmail.com>
Co-developed-by: Rodrigo Ribeiro <rodrigorsdc@gmail.com>
Reviewed-by: Matheus Tavares <matheus.bernardino@usp.br>
Reviewed-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>