mtd: rawnand: cadence: remove unused struct 'ecc_info'

'ecc_info' has been unused since the original
commit ec4ba01e ("mtd: rawnand: Add new Cadence NAND driver to MTD
subsystem").

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20240525202529.120792-1-linux@treblig.org