The main NAND read page function can loop over "page reads" many times
in if the reading reports uncorrectable error(s) and if the chip
supports the read_retry feature.

In this case, the number of bitflips is summarized between
attempts. Fix this by re-initializing the entire mtd_ecc_stats object
each time we retry.
Suggested-by: NBoris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: NMiquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: NBoris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/linux-mtd/20200519074549.23673-4-miquel.raynal@bootlin.com