drm/nouveau/kms/nv50-: Remove several set but not used variables "ret" in disp.c

Fixes the following warning when using W=1 to build kernel:

drivers/gpu/drm/nouveau/dispnv50/disp.c: In function ‘nv50_mstm_cleanup’:
drivers/gpu/drm/nouveau/dispnv50/disp.c:1389:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 1389 |  int ret;
      |      ^~~
drivers/gpu/drm/nouveau/dispnv50/disp.c: In function ‘nv50_mstm_prepare’:
drivers/gpu/drm/nouveau/dispnv50/disp.c:1413:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 1413 |  int ret;
      |      ^~~
Signed-off-by: Luo Jiaxing <luojiaxing@huawei.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://gitlab.freedesktop.org/drm/nouveau/-/merge_requests/10

drivers/gpu/drm/nouveau/dispnv50/disp.c

@@ -1387,12 +1387,11 @@ nv50_mstm_cleanup(struct nv50_mstm *mstm)
 {
 	struct nouveau_drm *drm = nouveau_drm(mstm->outp->base.base.dev);
 	struct drm_encoder *encoder;
-	int ret;
 
 	NV_ATOMIC(drm, "%s: mstm cleanup\n", mstm->outp->base.base.name);
-	ret = drm_dp_check_act_status(&mstm->mgr);
+	drm_dp_check_act_status(&mstm->mgr);
 
-	ret = drm_dp_update_payload_part2(&mstm->mgr);
+	drm_dp_update_payload_part2(&mstm->mgr);
 
 	drm_for_each_encoder(encoder, mstm->outp->base.base.dev) {
 		if (encoder->encoder_type == DRM_MODE_ENCODER_DPMST) {
@@ -1411,10 +1410,9 @@ nv50_mstm_prepare(struct nv50_mstm *mstm)
 {
 	struct nouveau_drm *drm = nouveau_drm(mstm->outp->base.base.dev);
 	struct drm_encoder *encoder;
-	int ret;
 
 	NV_ATOMIC(drm, "%s: mstm prepare\n", mstm->outp->base.base.name);
-	ret = drm_dp_update_payload_part1(&mstm->mgr);
+	drm_dp_update_payload_part1(&mstm->mgr);
 
 	drm_for_each_encoder(encoder, mstm->outp->base.base.dev) {
 		if (encoder->encoder_type == DRM_MODE_ENCODER_DPMST) {