mtd: fsl_ifc_nand: set NAND_NO_SUBPAGE_WRITE

This controller only does ECC on full-page accesses, even though the
ECC consists of multiple steps.  fsl_elbc_nand can get away with this
because the ECC of an all-0xff region will be all-0xff, but this is not
true with the ECC algorithms used by IFC.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>