drm/amd/display: Deadlock/HPD Status/Crash Bug Fix

[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>