The fix for errata workaround is to avoid covering physical address
0xff000000 to 0xffffffff during the implementation. Early commit eb672e92
works until DDR size exceeds 4GB. This fix works for DDR size up to 64GB.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>