ramips: correct page read return value of the mt7621 nand driver
read_page() need to return maximum number of bitflips instead of the
accumulated number. Change takes from upstream mt7621 u-boot [1].
* @read_page: function to read a page according to the ECC generator
* requirements; returns maximum number of bitflips
* corrected in any single ECC step, -EIO hw error
[1] https://lore.kernel.org/all/cover.
1653015383.git.weijie.gao@mediatek.com/
Signed-off-by: Shiji Yang <yangshiji66@qq.com>
(cherry picked from commit
2fbb91d73ffecc7d033e5bb0b550d664ef9e0f91)