ARM: tegra: nexus7: Use common LVDS display device-tree

Make Nexus 7 device-tree to use common LVDS bridge description. This makes
device-trees more consistent.

[digetx@gmail.com: factored Nexus7 change into separate patch and wrote commit message]

Signed-off-by: Maxim Schwalm <maxim.schwalm@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>