On HDCP disable, clear the repeater bit. This ensures if we connect a
non-repeater sink after a repeater, the bit is in the state we expect.

Fixes: ee5e5e7a ("drm/i915: Add HDCP framework + base implementation")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ramalingam C <ramalingam.c@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: intel-gfx@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v4.17+
Reviewed-by: Ramalingam C <ramalingam.c@intel.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20191212190230.188505-3-sean@poorly.run #v2
Link: https://patchwork.freedesktop.org/patch/msgid/20200117193103.156821-3-sean@poorly.run #v3
Link: https://patchwork.freedesktop.org/patch/msgid/20200218220242.107265-3-sean@poorly.run #v4
Link: https://patchwork.freedesktop.org/patch/msgid/20200305201236.152307-3-sean@poorly.run #v5
Link: https://patchwork.freedesktop.org/patch/msgid/20200429195502.39919-3-sean@poorly.run #v6
Link: https://patchwork.freedesktop.org/patch/msgid/20200623155907.22961-3-sean@poorly.run #v7

Changes in v2:
-Added to the set
Changes in v3:
-None
  I had previously agreed that clearing the rep_ctl bits on enable would
  also be a good idea. However when I committed that idea to code, it
  didn't look right. So let's rely on enables and disables being paired
  and everything outside of that will be considered a bug
Changes in v4:
-s/I915_(READ|WRITE)/intel_de_(read|write)/
Changes in v5:
-None
Changes in v6:
-None
Changes in v7:
-None
Changes in v8:
-None
Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200818153910.27894-3-sean@poorly.run