dt-bindings: mtd: sunxi: Prevent NAND chip unevaluated properties

nand-ecc-mode is a generic property which may apply to any raw NAND
chip, it does not need to be listed in each controller
description. Instead, let's reference the raw NAND chip description file
which contains the property. The description contained
"additionalProperties: false" which is wrong as other properties such as
partitions might very well be added in the final .dts, and anyway needs
to be converted into "unexpectedProperties: false" to fit the property
change new requirements.

Cc: Maxime Ripard <mripard@kernel.org>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: Samuel Holland <samuel@sholland.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/linux-mtd/20230619092916.3028470-9-miquel.raynal@bootlin.com