drm/msm/dp: move next_bridge handling to dp_display

Remove two levels of indirection and fetch next bridge directly in
dp_display_probe_tail().

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Tested-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/576126/
Link: https://lore.kernel.org/r/20240126-dp-power-parser-cleanup-v3-14-098d5f581dd3@linaro.org