[Why]
Fix problems when we disable secure_display.

[How]
- Reset secure display context after disabled
- A secure_display_context is dedicate to a crtc, so we set the crtc for
it when we create the context.
Reviewed-by: NWayne Lin <Wayne.Lin@amd.com>
Acked-by: NJasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: NAlan Liu <HaoPing.Liu@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>