ARM: tegra: Add device-tree for Pegatron Chagall

Add device-tree for Pegatron Chagall, which is a NVIDIA Tegra30-based
Android tablet.

Link: https://wiki.postmarketos.org/wiki/Pegatron_Chagall_(pegatron-chagall)


Co-developed-by: Raffaele Tranquillini <raffaele.tranquillini@gmail.com>
Signed-off-by: Raffaele Tranquillini <raffaele.tranquillini@gmail.com>
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>