drm/msm/dpu: remove node from list before freeing the node

fix the following smatch warning:
drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c:1675 dpu_plane_init() warn:
'&pdpu->mplane_list' not removed from list

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/1638502612-113708-1-git-send-email-yang.lee@linux.alibaba.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c

@@ -1672,6 +1672,7 @@ struct drm_plane *dpu_plane_init(struct drm_device *dev,
 	if (pdpu && pdpu->pipe_hw)
 		dpu_hw_sspp_destroy(pdpu->pipe_hw);
 clean_plane:
+	list_del(&pdpu->mplane_list);
 	kfree(pdpu);
 	return ERR_PTR(ret);
 }