drm/amd/display: Revert HDCP disable sequence change

[Why]
Revert HDCP disable sequence change that blanks stream before
disabling HDCP. PSP and HW teams are currently investigating the
root cause of why HDCP cannot be disabled before stream blank,
which is expected to work without issues.

Signed-off-by: Jaehyun Chung <jaehyun.chung@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>