drm/msm/dp: delete EV_HPD_INIT_SETUP

drm/msm/dp: delete EV_HPD_INIT_SETUP

EV_HPD_INIT_SETUP flag is used to trigger the initialization of external
DP host controller. Since external DP host controller initialization had
been incorporated into pm_runtime_resume(), this flag became obsolete.
msm_dp_irq_postinstall() which triggers EV_HPD_INIT_SETUP event is
obsoleted accordingly.

Changes in v4:
-- reworded commit text
-- drop EV_HPD_INIT_SETUP
-- drop msm_dp_irq_postinstall()

Changes in v3:
-- drop EV_HPD_INIT_SETUP and msm_dp_irq_postinstall()

Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/570075/
Link: https://lore.kernel.org/r/1701472789-25951-7-git-send-email-quic_khsieh@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>