driver/mtd/IFC: Add support of 8K page size NAND flash

Current IFC driver supports till 4K page size NAND flash.
Add support of 8K Page size NAND flash
  - Add nand_ecclayout for 4 bit & 8 bit ecc
  - Defines constants
  - also fix ecc.strength for 8bit ecc of 8K page size NAND

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>