Micron Nand Flash program operation not possible when ECC is enabled.

8 bits is not wide enough to use ECC. The ECC circuit stores additional data along with the 8 bits. I don't remember how many you need for 8 bit ECC, but it is at least 10 bits. Boards that use ECC have wider data widths to accommodate the ECC bits (e.g. 32 data bits + 4 ECC bits => 36 bit wide memory).You can't make ECC work for flash on this board because you don't have the extra data width.