ARM: tegra: Use Hannstar HSD101PWW2 on Pegatron Chagall

The LVDS bindings require a specific compatible string in addition to
the generic "panel-lvds". Add the HannStar HSD101PWW2 which is used on
a similar device (ASUS TF201) and seems to work fine with slightly
modified timings in DT.

Suggested-by: Svyatoslav Ryhel <clamor95@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>