drm/i915: HDCP state handling in ddi_update_pipe

The downgrade of the fullmodeset into fastset
intel_encoder->update_pipe, in possible scenario, skips the En/Dis-able
DDI. Hence breaks the HDCP state change handling.

We also don't have any hdcp tests in CI, because the shard runs don't
have hdcp capable outputs :-/

So this change fixs it by handling the HDCP state change request at
intel_encoder->update_pipe too along with enable and disable of the DDI.

Fixes: d19f958d ("drm/i915: Enable fastset for non-boot modesets.")

v2:
  Added commit id that broke the HDCP [Daniel]

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
cc: Hans de Goede <hdegoede@redhat.com>
cc: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1549295080-18353-1-git-send-email-ramalingam.c@intel.com