ARM: tegra: Add device-tree for ASUS Transformer Pad TF300TG

Add device-tree for ASUS Transformer Pad TF300TG, which is a NVIDIA
Tegra30-based 2-in-1 detachable, originally running Android. It's a
variant of the TF300T that has a 3G modem.

Link: https://wiki.postmarketos.org/wiki/ASUS_Transformer_Pad_(asus-tf300t)


Co-developed-by: Ion Agorria <ion@agorria.com>
Signed-off-by: Ion Agorria <ion@agorria.com>
Co-developed-by: Maxim Schwalm <maxim.schwalm@gmail.com>
Signed-off-by: Maxim Schwalm <maxim.schwalm@gmail.com>
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
[treding@nvidia.com: cosmetic fixups]
Signed-off-by: Thierry Reding <treding@nvidia.com>