layerscape: armv8_64b: add Traverse Ten64 NAND variant

layerscape: armv8_64b: add Traverse Ten64 NAND variant

The Ten64 board[1] is based around NXP's Layerscape LS1088A SoC.
It is capable of booting both standard Linux distributions
from disk devices, using EFI, and booting OpenWrt
from NAND.

See the online manual for more information, including the
flash layout[2].

This patchset adds support for generating Ten64 images
for NAND boot.
For disk boot, one can use the EFI support that was
recently added to the armvirt target.

We previously supported NAND users by building
inside our armvirt/EFI target[3], but this approach
is not suitable for OpenWrt upstream. Users who
used our supplied NAND images will be able to upgrade
to this via sysupgrade.

Signed-off-by: Mathew McBride <matt@traverse.com.au>
[1] - https://www.traverse.com.au/hardware/ten64
[2] - https://ten64doc.traverse.com.au/hardware/flash/
[3] - Example:
https://gitlab.com/traversetech/ls1088firmware/openwrt/-/commit/285e4360e1604eb466880d245d48efd9962143a5