drm/panel: Add support for Ampire AM-800480R3TMQW-A1H 800x480 7" panel

This adds support for the AM-800480R3TMQW-A1H 7" 800x480 panel to the
DRM simple panel driver.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>