drm/i915: Remove old PSR2 FIXME about frontbuffer tracking

Our frontbuffer tracking improved over the years + the WA #0884
helped us keep PSR2 enabled while triggering screen updates when
necessary so this FIXME is not valid anymore.
Acked-by: NDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NJosé Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181204003403.23361-6-jose.souza@intel.com

drivers/gpu/drm/i915/intel_psr.c

@@ -476,9 +476,6 @@ static void hsw_activate_psr2(struct intel_dp *intel_dp)
 	idle_frames = max(idle_frames, dev_priv->psr.sink_sync_latency + 1);
 	val = idle_frames << EDP_PSR2_IDLE_FRAME_SHIFT;
 
-	/* FIXME: selective update is probably totally broken because it doesn't
-	 * mesh at all with our frontbuffer tracking. And the hw alone isn't
-	 * good enough. */
 	val |= EDP_PSR2_ENABLE | EDP_SU_TRACK_ENABLE;
 	if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv))
 		val |= EDP_Y_COORDINATE_ENABLE;