mfd: stmfx: Fix dev_err_probe() call in stmfx_chip_init()

'ret' may be 0 so, dev_err_probe() should be called only when 'ret' is
an error code.

Fixes: 41c9c06c ("mfd: stmfx: Simplify with dev_err_probe()")
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/stmfx.c

@@ -329,11 +329,11 @@ static int stmfx_chip_init(struct i2c_client *client)
 
 	stmfx->vdd = devm_regulator_get_optional(&client->dev, "vdd");
 	ret = PTR_ERR_OR_ZERO(stmfx->vdd);
-	if (ret == -ENODEV) {
-		stmfx->vdd = NULL;
-	} else {
-		return dev_err_probe(&client->dev, ret,
-				     "Failed to get VDD regulator\n");
+	if (ret) {
+		if (ret == -ENODEV)
+			stmfx->vdd = NULL;
+		else
+			return dev_err_probe(&client->dev, ret, "Failed to get VDD regulator\n");
 	}
 
 	if (stmfx->vdd) {