arm64: dts: meson: libretech: update board model

There is actually several different libretech board with the CC suffix
so the model name is not appropriate here. Update to something more
specific

Reported-by: Da Xue <da@lessconfused.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>