mfd: stmfx: Improve error message triggered by regulator fault in .remove()

Returning a non-zero value in an i2c remove callback results in the i2c
core emitting a very generic error message ("remove failed (-ESOMETHING),
will be ignored") and as the message indicates not further error handling
is done.

Instead emit a more specific error message and then return zero in
.remove().

The long-term goal is to make the i2c remove prototype return void, making
all implementations return 0 is preparatory work for this change.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220214150710.312269-1-u.kleine-koenig@pengutronix.de

drivers/mfd/stmfx.c

@@ -392,17 +392,22 @@ err:
 	return ret;
 }
 
-static int stmfx_chip_exit(struct i2c_client *client)
+static void stmfx_chip_exit(struct i2c_client *client)
 {
 	struct stmfx *stmfx = i2c_get_clientdata(client);
 
 	regmap_write(stmfx->map, STMFX_REG_IRQ_SRC_EN, 0);
 	regmap_write(stmfx->map, STMFX_REG_SYS_CTRL, 0);
 
-	if (stmfx->vdd)
-		return regulator_disable(stmfx->vdd);
+	if (stmfx->vdd) {
+		int ret;
 
-	return 0;
+		ret = regulator_disable(stmfx->vdd);
+		if (ret)
+			dev_err(&client->dev,
+				"Failed to disable vdd regulator: %pe\n",
+				ERR_PTR(ret));
+	}
 }
 
 static int stmfx_probe(struct i2c_client *client,
@@ -466,7 +471,9 @@ static int stmfx_remove(struct i2c_client *client)
 {
 	stmfx_irq_exit(client);
 
-	return stmfx_chip_exit(client);
+	stmfx_chip_exit(client);
+
+	return 0;
 }
 
 #ifdef CONFIG_PM_SLEEP