armv8: mmu: fix page table mapping

To page mapping the lowest 2 bits needs to be 0x3.
If not fix this, the final lowest 3 bits for page mapping is 0x1
which is marked as reserved.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>