drm/amd/display: only enable HDCP for DCN+

[Why]
We don't support HDCP for pre RAVEN asics

[How]
Check if we are RAVEN+. Use this to attach the content_protection
property, this way usermode can't try to enable HDCP on pre DCN asics.

Also we need to update the module on hpd so guard it aswell

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>