drm/msm/hdmi: support attaching the "next" bridge

drm/msm/hdmi: support attaching the "next" bridge

There might be a chain of bridges attached to the HDMI node
(including but not limited to the display-connector bridge). Add support
for attaching them right to the HDMI bridge chain.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/489709/
Link: https://lore.kernel.org/r/20220616085057.432353-1-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>