The mxs nand driver has a calculation for the ecc strength.
This calculation was not used for some common nands and it
was assumed that 2k page nands always have a ecc strength
of 8. This is not true since there are devices with 224 bytes
of oob instread of 64 bytes. These allow for a greater ecc
strength. Since the kernel relies on the calculation and
we have to be consistent with the kernel use the calculcation
in barebox aswell and just remove our assumptions.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>