mtd: rawnand: ingenic: Move BBTs out of ECC area

The generic layout for BBT markers will most likely overlap with our
ECC bytes in the OOB, so move the BBT markers outside the OOB area.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>