drm/panel: samsung-s6d7aa0: Add MODULE_DEVICE_TABLE

The driver can be built as a module, however the lack of the
MODULE_DEVICE_TABLE macro prevents it from being automatically probed
from the DT in such case.

Add the missed macro to make sure the module can load automatically.

Fixes: 6810bb39

 ("drm/panel: Add Samsung S6D7AA0 panel controller driver")
Signed-off-by: Nikita Travkin <nikita@trvn.ru>
Acked-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/20230802-gt5-panel-dtable-v1-1-c0a765c175e2@trvn.ru