drm/i915: Beef up of Beef up the IPS vs. CRC workaround

Commit 6e644626 ("drm/i915: Beef up the IPS vs. CRC
workaround") was supposed to solve below bug. However, the
patch I tested is not the same as the one that got merged.
With this addition the test pass.

V2: removed unused: "struct intel_crtc *intel_crtc"

Fixes: 6e644626 ("drm/i915: Beef up the IPS vs. CRC workaround")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101664


Signed-off-by: Marta Lofstedt <marta.lofstedt@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170828121810.13112-1-marta.lofstedt@intel.com