mtd: nand: ecc-bch: Update the prototypes to be more generic

These functions must be usable by the main NAND core, so their names
must be technology-agnostic as well as the parameters. Hence, we pass
a generic nand_device instead of a raw nand_chip structure.

As it seems that changing the raw NAND functions to always pass a
generic NAND device is a lost of time, we prefer to create dedicated
raw NAND wrappers that will be useful in the near future to do the
translation.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200929230124.31491-8-miquel.raynal@bootlin.com