mtd: sh_flctl: Use user oob data in hardware ECC mode

In hardware ecc mode, the flctl now writes and reads the oob data
provided by the user. Additionally the ECC is now returned in normal
page reads, not only when using the explicit NAND_CMD_READOOB command.

Signed-off-by: Bastian Hecht <hechtb@gmail.com>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>