i2c: mux: demux-pinctrl: check the return value of devm_kstrdup()

devm_kstrdup() returns pointer to allocated string on success,
NULL on failure. So it is better to check the return value of it.

Fixes: e35478e ("i2c: mux: demux-pinctrl: run properly with multiple instances")
Signed-off-by: Xiaoke Wang <xkernel.wang@foxmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/muxes/i2c-demux-pinctrl.c

@@ -243,6 +243,10 @@ static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
 
 		props[i].name = devm_kstrdup(&pdev->dev, "status", GFP_KERNEL);
 		props[i].value = devm_kstrdup(&pdev->dev, "ok", GFP_KERNEL);
+		if (!props[i].name || !props[i].value) {
+			err = -ENOMEM;
+			goto err_rollback;
+		}
 		props[i].length = 3;
 
 		of_changeset_init(&priv->chan[i].chgset);