mtd: nand/fsmc: Flip the bit only if the error index is < 4096
ECC can correct up to 8 bits in 512 bytes data + 13 bytes ecc. This means that
the algorithm can correct a max of 8 bits in 4200 bits ie the error indices can
be from 0 to 4199. Of these 0 to 4095 are for data and 4096 to 4199 for ecc.
The driver flips the bit only if the index is <= 4096. This is a bug since the
data bits are only from 0 to 4095.