mtd: rawnand: Ensure ECC configuration is propagated to upper layers

Until recently the "upper layer" was MTD. But following incremental
reworks to bring spi-nand support and more recently generic ECC support,
there is now an intermediate "generic NAND" layer that also needs to get
access to some values. When using "converted" ECC engines, like the
software ones, these values are already propagated correctly. But
otherwise when using good old raw NAND controller drivers, we need to
manually set these values ourselves at the end of the "scan" operation,
once these values have been negotiated.

Without this propagation, later (generic) checks like the one warning
users that the ECC strength is not high enough might simply no longer
work.

Fixes: 8c126720

 ("mtd: rawnand: Use the ECC framework nand_ecc_is_strong_enough() helper")
Cc: stable@vger.kernel.org
Reported-by: Sascha Hauer <s.hauer@pengutronix.de>
Closes: https://lore.kernel.org/all/Zhe2JtvvN1M4Ompw@pengutronix.de/
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Tested-by: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://lore.kernel.org/linux-mtd/20240507085842.108844-1-miquel.raynal@bootlin.com