mtd: nand: Update dependency of IFC for LS1021A

As NAND support for Freescale/NXP IFC controller is available on
LS1021A, the dependency for LS1021A is added.

LS1021A is an earlier product and is not compatible with later
LayerScape architecture. So ARCH_LAYERSCAPE can't cover LS1021A.

Signed-off-by: Alison Wang <alison.wang@nxp.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>