Convert the NAU8540 audio CODEC bindings to DT schema

Signed-off-by: Anup Sharma <anupnewsmail@gmail.com

Changes:
V1 -> V2: Adhere to the correct procedure by including the maintainer's name.
          Drop Mark from maintainer.

Link: https://lore.kernel.org/r/ZFYxWVdE9YkMKvXv@yoga
Signed-off-by: Mark Brown <broonie@kernel.org