drm/panel: simple: Add support for the LeMaker BL035-RGB-002 3.5" LCD

This adds support for the 3.5" LCD panel from LeMaker, sold for use with
BananaPi boards. It comes with a 24-bit RGB888 parallel interface and
requires an active-low DE signal

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181107181843.27628-7-contact@paulk.fr