drm/simpledrm: Do not call drm_atomic_add_affected_planes()

There's no need to add planes to the atomic state. Remove the call
to drm_atomic_add_affected_planes() from simpledrm.

On full modesets, the DRM helpers already add a CRTC's planes to the
atomic state; see drm_atomic_helper_check_modeset(). There's no reason
to call drm_atomic_add_affected_planes() unconditionally in the CRTC's
atomic_check() in simpledrm. It's also too late, as the atomic_check()
of the added planes will not be called before the commit.
Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20221011165136.469750-3-javierm@redhat.com

drivers/gpu/drm/tiny/simpledrm.c

@@ -549,17 +549,11 @@ static int simpledrm_crtc_helper_atomic_check(struct drm_crtc *crtc,
 					      struct drm_atomic_state *new_state)
 {
 	struct drm_crtc_state *new_crtc_state = drm_atomic_get_new_crtc_state(new_state, crtc);
-	int ret;
 
 	if (!new_crtc_state->enable)
-		goto out;
-
-	ret = drm_atomic_helper_check_crtc_primary_plane(new_crtc_state);
-	if (ret)
-		return ret;
+		return 0;
 
-out:
-	return drm_atomic_add_affected_planes(new_state, crtc);
+	return drm_atomic_helper_check_crtc_primary_plane(new_crtc_state);
 }
 
 /*