armv8: fsl-layerscape: change tlb base from OCRAM to DDR in EL < 3

Change tlb base address from OCRAM to DDR when exception level is
less than 3.

Signed-off-by: Ruchika Gupta <ruchika.gupta@nxp.com>
Signed-off-by: Pankit Garg <pankit.garg@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>