board: lg: x3: add Optimus 4X HD and Optimus Vu support

LG X3 is a development board based on Nvidia Tegra 3 SoC
on base of which Optimus 4X HD and Optimus Vu were created.
Both smartphones feature a 4.7" and 5" panels respectively,
an Nvidia Tegra 3 quad-core chip, 1 GB of RAM and 16/32 GB
of internal storage. Optimux 4X HD additionally has a micro
SD slot.

Tested-by: Andreas Westman Dorcsak <hedmoo@yahoo.com> # LG P880 T30
Tested-by: Svyatoslav Ryhel <clamor95@gmail.com> # LG P895 T30
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>