dt-bindings: rng: sparc_sun_oracle_rng: convert to DT schema

Convert the Devicetree binding documentation for:
* SUNW,n2-rng
* SUNW,vf-rng
* SUNW,kt-rng
* ORCL,m4-rng
* ORCL,m7-rng
from plain text to YAML.

Signed-off-by: Kael D'Alcamo <dev@kael-k.io>
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>