gpio: pcf857x: Simpify wake-up handling

Unlike gpio_rcar_irq_set_wake(), which this solution was based on,
pcf857x_irq_set_wake() does not need to do anything else than calling
irq_set_irq_wake() for the upstream interrupt controller.  Hence there
is no reason for making this call conditional, and no longer a need for
keeping a copy of the interrupt number that also serves as a flag.

Just propagate irq_set_irq_wake() to the upstream interrupt controller,
using the original interrupt number.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-pcf857x.c

@@ -88,7 +88,6 @@ struct pcf857x {
 	struct mutex		lock;		/* protect 'out' */
 	unsigned		out;		/* software latch */
 	unsigned		status;		/* current status */
-	unsigned int		irq_parent;
 	unsigned		irq_enabled;	/* enabled irqs */
 
 	int (*write)(struct i2c_client *client, unsigned data);
@@ -210,18 +209,7 @@ static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on)
 {
 	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
 
-	int error = 0;
-
-	if (gpio->irq_parent) {
-		error = irq_set_irq_wake(gpio->irq_parent, on);
-		if (error) {
-			dev_dbg(&gpio->client->dev,
-				"irq %u doesn't support irq_set_wake\n",
-				gpio->irq_parent);
-			gpio->irq_parent = 0;
-		}
-	}
-	return error;
+	return irq_set_irq_wake(gpio->client->irq, on);
 }
 
 static void pcf857x_irq_enable(struct irq_data *data)
@@ -394,7 +382,6 @@ static int pcf857x_probe(struct i2c_client *client,
 
 		gpiochip_set_nested_irqchip(&gpio->chip, &pcf857x_irq_chip,
 					    client->irq);
-		gpio->irq_parent = client->irq;
 	}
 
 	/* Let platform code set up the GPIOs and their users.