drm/panel: nt36523: fix return value check in nt36523_probe()

mipi_dsi_device_register_full() never returns NULL pointer, it
will return ERR_PTR() when it fails, so replace the check with
IS_ERR().

Fixes: 0993234a ("drm/panel: Add driver for Novatek NT36523")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20231129090715.856263-1-yangyingliang@huaweicloud.comSigned-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231129090715.856263-1-yangyingliang@huaweicloud.com

drivers/gpu/drm/panel/panel-novatek-nt36523.c

@@ -1254,9 +1254,9 @@ static int nt36523_probe(struct mipi_dsi_device *dsi)
 			return dev_err_probe(dev, -EPROBE_DEFER, "cannot get secondary DSI host\n");
 
 		pinfo->dsi[1] = mipi_dsi_device_register_full(dsi1_host, info);
-		if (!pinfo->dsi[1]) {
+		if (IS_ERR(pinfo->dsi[1])) {
 			dev_err(dev, "cannot get secondary DSI device\n");
-			return -ENODEV;
+			return PTR_ERR(pinfo->dsi[1]);
 		}
 	}