dm: i2c: Add a missing memory allocaton check

This strdup() is missing a check. Add it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c
index a6991bf..b890806 100644
--- a/drivers/i2c/i2c-uclass.c
+++ b/drivers/i2c/i2c-uclass.c
@@ -230,6 +230,8 @@
 
 	snprintf(name, sizeof(name), "generic_%x", chip_addr);
 	str = strdup(name);
+	if (!str)
+		return -ENOMEM;
 	ret = device_bind_driver(bus, "i2c_generic_chip_drv", str, &dev);
 	debug("%s:  device_bind_driver: ret=%d\n", __func__, ret);
 	if (ret)