dt-bindings: mtd: nvidia,tegra20-nand: convert to DT schema

dt-bindings: mtd: nvidia,tegra20-nand: convert to DT schema

Convert NVIDIA Tegra NAND Flash Controller binding to YAML format.
Changes during Conversion:
- Define new properties `power-domains` and `operating-points-v2`
  because the existing in tree DTS uses them.
- Modify MAINTAINERS references to point the created YAML file.

Signed-off-by: Charan Pedumuru <charan.pedumuru@gmail.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>