armv8: ls1046ardb: Enable IFC for SPL build

Commit a52ff334 ("armv8: ls1046ardb: SPL size reduction") reduced
image size for SPL. IFC was disabled. If PPA is loaded in SPL, MMU is
enabled as a result. Removing IFC skips IFC region in the MMU table,
causing later failure in RAM version U-boot when accessing CPLD
through IFC. Only disable IFC if PPA is not enabled for SPL.

Signed-off-by: York Sun <york.sun@nxp.com>