mtd: rawnand: atmel: Update ecc_stats.corrected counter

Update MTD ECC statistics with the number of corrected bits.

Fixes: f88fc122 ("mtd: nand: Cleanup/rework the atmel_nand driver")
Cc: stable@vger.kernel.org
Signed-off-by: Kai Stuhlemmer (ebee Engineering) <kai.stuhlemmer@ebee.de>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210322150714.101585-1-tudor.ambarus@microchip.com