drm/panel: simple: Add Sharp LQ070Y3DG3B panel support

The change adds support for the Sharp LQ070Y3DG3B 7.0" TFT LCD panel.

Tested on Letux7004.

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/d16aaa1ac93e4f15c13cd7d621de95836257676a.1559905870.git.hns@goldelico.com