drm/panel: Add Samsung S6D7AA0 panel controller driver

Initial driver for S6D7AA0-controlled panels. Currently, the following
panels are supported:

 - S6D7AA0-LSL080AL02 (Samsung Galaxy Tab 3 8.0)
 - S6D7AA0-LSL080AL03 (Samsung Galaxy Tab A 8.0 2015)
 - S6D7AA0-LTL101AT01 (Samsung Galaxy Tab A 9.7 2015)

It should be possible to extend this driver to work with other panels
using this IC.

Tested-by: Nikita Travkin <nikita@trvn.ru> #ltl101at01
Signed-off-by: Artur Weber <aweber.kernel@gmail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230519170354.29610-3-aweber.kernel@gmail.com