Add NULL check before dereferencing pointer of_id in order to avoid
a potential NULL pointer dereference.
Addresses-Coverity-ID: 
1408829
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
 
        if (i2c->dev.of_node) {
                of_id = of_match_device(wm831x_of_match, &i2c->dev);
+               if (!of_id) {
+                       dev_err(&i2c->dev, "Failed to match device\n");
+                       return -ENODEV;
+               }
                type = (enum wm831x_parent)of_id->data;
        } else {
                type = (enum wm831x_parent)id->driver_data;