[why]
1. HPD callback function has deadlock problem
2. HPD status is not assigned
3. There is crash due to null pointer
4. link_enc is NULL in DPIA case
[How]
1. Fix deadlock problem by moving it out of the
drm_modeset_lock
2. Assign HPD status from the notify of outbox
from dmub FW
3. Fix the crash by checking if pin or enc exists
4. Use link_enc_cfg_get_link_enc_used_by_link to
dynamically assign
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com> Acked-by: Wayne Lin <Wayne.Lin@amd.com> Acked-by: Harry Wentland <harry.wentland@amd.com> Signed-off-by: Jude Shih <shenshih@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>