arm: layerscape: Don't select FSL_IFC when booting from SD card

FSL_IFC should only be selected when booting from NAND flash (or when
NAND_FSL_IFC is enabled). The existing logic does this correctly when
QSPI is also enabled, but not when just booting from SD.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>