drm/msm/dp: update HDCP stream de-registration logic

Extend HDCP stream de-registration code to provide virtual channel
ID in addition to the stream id. Also fix flaw in de-registration
logic that resulted in HDCP off being skipped in valid cases.

Change-Id: Iee10193130ca0071b8136e4abade2ba35af20332
Signed-off-by: Christopher Braga <cbraga@codeaurora.org>