drm/amd/display: Update CP property based on HW query

drm/amd/display: Update CP property based on HW query

[Why]
We need to use HW state to set content protection to ENABLED.
This way we know that the link is encrypted from the HW side

[How]
Create a workqueue that queries the HW every ~2seconds, and sets it to
ENABLED or DESIRED based on the result from the hardware

Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>