uboot-phytec

x86: qemu: Support getting high memory size

At present only size of memory that is below 4GiB is retrieved from
QEMU. Add a function that gets size of memory that is above 4GiB.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Aiden Park <aiden.park@intel.com>