drm/panel: Add driver for Truly panel with R65530 IC

It adds a drm panel driver for Truly panel with R65530 driver IC.  It
supports not only Truly panel but also panel from AUO that is integrated
with a R65530 driver IC, although the driver is named after Truly.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>