The commit bf4289cb removed the use of
CONFIG_MTD_NAND_ATMEL_ECC_NONE and CONFIG_MTD_NAND_ATMEL_ECC_HW but the
Kconfig file was forgotten.

This patch remove those inoperative options.
Signed-off-by: NRichard Genoud <richard.genoud@gmail.com>
Signed-off-by: NNicolas Ferre <nicolas.ferre@atmel.com>