drm/i915: Zap call to drm_plane_helper_disable, v2.

The primary plane can still be configured when crtc is off,
furthermore this is also a noop now that affected planes are
added on modesets.

Changes since v1:
- Move commit so no frontbuffer_bits warnings are generated.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: NMatt Roper <matthew.d.roper@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -12938,8 +12938,6 @@ static int __intel_set_mode(struct drm_atomic_state *state)
 
 		intel_crtc_disable_planes(crtc);
 		dev_priv->display.crtc_disable(crtc);
-		if (!crtc_state->enable)
-			drm_plane_helper_disable(crtc->primary);
 	}
 
 	/* Only after disabling all output pipelines that will be changed can we