drm/bridge: lt9611uxc: properly attach to a next bridge

If there is a next bridge in the OF graph don't let it be ignored.
Attach the next bridge to the chain.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240701-lt9611uxc-next-bridge-v1-1-665bce5fdaaa@linaro.org