drm/atomic: Use drm_drv_uses_atomic_modeset() for debugfs creation

As pointed out by Daniel Vetter, we should be usinng
drm_drv_uses_atomic_modeset() for determining whether or not we want to
make the debugfs nodes for atomic instead of checking DRIVER_ATOMIC, as
the former isn't an accurate representation of whether or not the driver
is actually using atomic modesetting internally (even though it might
not be exposing atomic capabilities).

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180917173733.21293-1-lyude@redhat.com

drivers/gpu/drm/drm_atomic.c

@@ -2067,7 +2067,7 @@ static void __drm_state_dump(struct drm_device *dev, struct drm_printer *p,
 	struct drm_connector *connector;
 	struct drm_connector_list_iter conn_iter;
 
-	if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
+	if (!drm_drv_uses_atomic_modeset(dev))
 		return;
 
 	list_for_each_entry(plane, &config->plane_list, head) {

drivers/gpu/drm/drm_debugfs.c

@@ -151,7 +151,7 @@ int drm_debugfs_init(struct drm_minor *minor, int minor_id,
 		return ret;
 	}
 
-	if (drm_core_check_feature(dev, DRIVER_ATOMIC)) {
+	if (drm_drv_uses_atomic_modeset(dev)) {
 		ret = drm_atomic_debugfs_init(minor);
 		if (ret) {
 			DRM_ERROR("Failed to create atomic debugfs files\n");