drm/bridge: lt9611uxc: Add MODULE_FIRMWARE macro

The module loads firmware so add a MODULE_FIRMWARE macro to provide that
information via modinfo.

Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230620061254.1210248-1-juerg.haefliger@canonical.com