drm/i915: Handle failure from 2nd stage HDCP auth

We enable the HDCP encryption as a part of first stage authentication.
So when second stage authentication fails, we need to disable the HDCP
encryption and signalling.

This patch ensures that, when hdcp authentication fails, HDCP encryption
and signalling is turned off.

v2:
  Dropped connector ref passing to auth [Seanpaul]
  Moved the call to disable_hdcp() to enable_hdcp() [Seanpaul]

v3:
  No Changes. Added the Reveiwed-by tag.
Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1517609350-10698-2-git-send-email-ramalingam.c@intel.com

drivers/gpu/drm/i915/intel_hdcp.c

@@ -562,6 +562,9 @@ static int _intel_hdcp_enable(struct intel_connector *connector)
 			      connector->hdcp_shim);
 	if (ret) {
 		DRM_ERROR("Failed to authenticate HDCP (%d)\n", ret);
+
+		/* Ensuring HDCP encryption and signalling are stopped. */
+		_intel_hdcp_disable(connector);
 		return ret;
 	}