drm/simpledrm: Remove !fb check from atomic_update

The primary plane implements atomic_disable, so atomic_update will
not be called without a framebuffer set. Remove the test for !fb.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220922130944.27138-4-tzimmermann@suse.de

drivers/gpu/drm/tiny/simpledrm.c

@@ -482,9 +482,6 @@ static void simpledrm_primary_plane_helper_atomic_update(struct drm_plane *plane
 	struct drm_rect src_clip, dst_clip;
 	int idx;
 
-	if (!fb)
-		return;
-
 	if (!drm_atomic_helper_damage_merged(old_plane_state, plane_state, &src_clip))
 		return;