uboot-imx

sunxi_nand_spl: Use kernel driver algorithm for determining ecc_mode / _off

Sync the code for figuring out the ecc_mode and ecc_offset with the linux
kernel v4.1. Keeping this in sync seems like a good idea in general, and
it fixes / adds support for ecc strengths of 56, 60 and 64 bits.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>