mtd: denali: Remove set_ecc_config function

set_ecc_config function only set ECC_CORRECTION register, so
move register setting to probe function.
Since controller only support 15bit and 8bit ecc correction,
updated nand ecc layout information.

Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>