This patch allows u-boot to expose the complete DDR region(s) to Linux
(after subtracting the memory hidden via MEM_TOP_HIDE mechanism).

This allows the u-boot to support the 48-bit VA support provided by
ARM64 Linux in flavors 3.18 and above, by passing the appropriate
'memory' DTS nodes.

Signed-off-by: Bhupesh Sharma <bhupesh.sharma at freescale.com>
Signed-off-by: Prabhakar Kushwaha <prabhakar at freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>