drm/msm/dsi: Add missing check for alloc_ordered_workqueue

Add check for the return value of alloc_ordered_workqueue as it may return
NULL pointer and cause NULL pointer dereference.
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/517646/
Link: https://lore.kernel.org/r/20230110021651.12770-1-jiasheng@iscas.ac.cnSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/dsi/dsi_host.c

@@ -1977,6 +1977,9 @@ int msm_dsi_host_init(struct msm_dsi *msm_dsi)
 
 	/* setup workqueue */
 	msm_host->workqueue = alloc_ordered_workqueue("dsi_drm_work", 0);
+	if (!msm_host->workqueue)
+		return -ENOMEM;
+
 	INIT_WORK(&msm_host->err_work, dsi_err_worker);
 
 	msm_dsi->id = msm_host->id;