mtd: set ONFI nand's default hooks in nand_set_defaults()

We may do some ONFI get/set features operations before we call the
nand_scan_tail().

So move the default ONFI nand hooks into nand_set_defaults().

Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>