drm/bridge: add missing MODULE_DESCRIPTION() macros

make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/bridge/lontium-lt9611.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/bridge/lontium-lt9611uxc.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/bridge/sil-sii8620.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/bridge/sii9234.o

Add the missing invocations of the MODULE_DESCRIPTION() macro.

Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240609-md-drivers-gpu-drm-bridge-v1-1-b582c5c815d7@quicinc.com