Revert "drm/i915: Add primary plane to mask if it's visible"

This reverts commit 721a09f739.

There is nothing wrong with the commit per se. We had two versions of
the commit, one in -next headed for v4.4 and this one for v4.3. Turns
out we'll need to backport more fixes from -next, and they conflict with
the v4.3 version. It gets messy. It will be easiest to revert this one,
and backport all the relevant commits from -next without modifications;
they apply cleanly after this revert.

Requested-by: Joseph Yasi <joe.yasi@gmail.com>
References: https://bugs.freedesktop.org/show_bug.cgi?id=91910#c4
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -15101,12 +15101,9 @@ static void readout_plane_state(struct intel_crtc *crtc,
 
 		plane_state = to_intel_plane_state(p->base.state);
 
-		if (p->base.type == DRM_PLANE_TYPE_PRIMARY) {
+		if (p->base.type == DRM_PLANE_TYPE_PRIMARY)
 			plane_state->visible = primary_get_hw_state(crtc);
-			if (plane_state->visible)
-				crtc->base.state->plane_mask |=
-					1 << drm_plane_index(&p->base);
-		} else {
+		else {
 			if (active)
 				p->disable_plane(&p->base, &crtc->base);