Marketing names are fungible. If nouveau says it's a NV106, then it's a NV106.
If it's truly not, then the hw maker screwed up -- unlikely. Also GK208B is
something we largely invented -- they're all marketed as GK208, but the "BOOT0"
register has a different chip id.

You can reuse the same firmware files as nv108 for nv106 -- can just symlink
them, ought to work.