drm/bridge: implement generic DP HPD bridge

Several USB-C controllers implement a pretty simple DRM bridge which
implements just the HPD notification operations. Add special helper
for creating such simple bridges.

Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231203114333.1305826-5-dmitry.baryshkov@linaro.org