armv8: Add generic smbios information into the device tree

armv8: Add generic smbios information into the device tree

Add common smbios information that can be used by all armv8
platforms and set it as default for qemu-arm64.
>From now smbios library can load values from here for those fields
doesn't exist in the sysinfo driver.

To run this with QEMU arm64, we need to dump the generated DTB
from QEMU first, merge it with the one we build and then re-run
QEMU with the merged DTB.
```
qemu-system-aarch64 -machine virt -machine dumpdtb=qemu.dtb
cat  <(dtc -I dtb qemu.dtb) <(dtc -I dtb ./dts/dt.dtb | \
  grep -v /dts-v1/) | dtc - -o merged.dtb
qemu-system-aarch64 -machine virt -nographic -bios u-boot.bin \
  -dtb merged.dtb
```
For details please take reference on dt_qemu.rst

Signed-off-by: Raymond Mao <raymond.mao@linaro.org>