drm/msm/dp: fix connect/disconnect handled at irq_hpd

drm/msm/dp: fix connect/disconnect handled at irq_hpd

Some usb type-c dongle use irq_hpd request to perform device connection
and disconnection. This patch add handling of both connection and
disconnection are based on the state of hpd_state and sink_count.

Changes in V2:
-- add dp_display_handle_port_ststus_changed()
-- fix kernel test robot complaint

Changes in V3:
-- add encoder_mode_set into struct dp_display_private

Reported-by: kernel test robot <lkp@intel.com>
Fixes: b9c2004ea729 ("drm/msm/dp: promote irq_hpd handle to handle link training correctly")
Tested-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>