drm/imx: legacy-bridge: add MODULE_DESCRIPTION

Every module should have a description, without this we get a
build time warning.

Fixes: cc3e8a21 ("drm/imx: add internal bridge handling display-timings DT node")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241015073004.4066457-2-arnd@kernel.org