drm/nouveau/fbcon: bracket entrypoints with a per-device enabled check

We don't necessarily have fbcon on all devices these days.

Fixes suspend on (at least) Quadro NVS 450.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_fbcon.c

@@ -503,23 +503,30 @@ nouveau_fbcon_fini(struct drm_device *dev)
 	drm->fbcon = NULL;
 }
 
-void nouveau_fbcon_save_disable_accel(struct drm_device *dev)
+void
+nouveau_fbcon_save_disable_accel(struct drm_device *dev)
 {
 	struct nouveau_drm *drm = nouveau_drm(dev);
-
+	if (drm->fbcon) {
 		drm->fbcon->saved_flags = drm->fbcon->helper.fbdev->flags;
 		drm->fbcon->helper.fbdev->flags |= FBINFO_HWACCEL_DISABLED;
+	}
 }
 
-void nouveau_fbcon_restore_accel(struct drm_device *dev)
+void
+nouveau_fbcon_restore_accel(struct drm_device *dev)
 {
 	struct nouveau_drm *drm = nouveau_drm(dev);
+	if (drm->fbcon) {
 		drm->fbcon->helper.fbdev->flags = drm->fbcon->saved_flags;
+	}
 }
 
-void nouveau_fbcon_set_suspend(struct drm_device *dev, int state)
+void
+nouveau_fbcon_set_suspend(struct drm_device *dev, int state)
 {
 	struct nouveau_drm *drm = nouveau_drm(dev);
+	if (drm->fbcon) {
 		console_lock();
 		if (state == 0)
 			nouveau_fbcon_save_disable_accel(dev);
@@ -527,10 +534,14 @@ void nouveau_fbcon_set_suspend(struct drm_device *dev, int state)
 		if (state == 1)
 			nouveau_fbcon_restore_accel(dev);
 		console_unlock();
+	}
 }
 
-void nouveau_fbcon_zfill_all(struct drm_device *dev)
+void
+nouveau_fbcon_zfill_all(struct drm_device *dev)
 {
 	struct nouveau_drm *drm = nouveau_drm(dev);
+	if (drm->fbcon) {
 		nouveau_fbcon_zfill(dev, drm->fbcon);
+	}
 }