drm/i915/guc: Remove stale comment for q_fail

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Fixes: 774439e1 ("drm/i915/guc: re-optimise i915_guc_client layout")
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170518113104.54400-1-michal.wajdeczko@intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
(cherry picked from commit 4afc67be8e)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_uc.h

@@ -59,8 +59,6 @@ struct drm_i915_gem_request;
  *                available in the work queue (note, the queue is shared,
  *                not per-engine). It is OK for this to be nonzero, but
  *                it should not be huge!
- *   q_fail: failed to enqueue a work item. This should never happen,
- *           because we check for space beforehand.
  *   b_fail: failed to ring the doorbell. This should never happen, unless
  *           somehow the hardware misbehaves, or maybe if the GuC firmware
  *           crashes? We probably need to reset the GPU to recover.