gpio: gpio-max710x: Support device tree probing

For probing via device tree, we need to support the case without platform_data.
In this case, chip.base is set to -1 for automatic numbering.

Signed-off-by: Roland Stigge <[e-mail]>
Acked-by: Wolfram Sang <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpio-max730x.c

···
 	int i, ret;
 
 	pdata = dev->platform_data;
-	if (!pdata || !pdata->base) {
-		dev_err(dev, "incorrect or missing platform data\n");
-		return -EINVAL;
-	}
 
 	mutex_init(&ts->lock);
 	dev_set_drvdata(dev, ts);
···
 	/* Power up the chip and disable IRQ output */
 	ts->write(dev, 0x04, 0x01);
 
-	ts->input_pullup_active = pdata->input_pullup_active;
+	if (pdata) {
+		ts->input_pullup_active = pdata->input_pullup_active;
+		ts->chip.base = pdata->base;
+	} else {
+		ts->chip.base = -1;
+	}
 	ts->chip.label = dev->driver->name;
 
 	ts->chip.direction_input = max7301_direction_input;
···
 	ts->chip.direction_output = max7301_direction_output;
 	ts->chip.set = max7301_set;
 
-	ts->chip.base = pdata->base;
 	ts->chip.ngpio = PIN_NUMBER;
 	ts->chip.can_sleep = 1;
 	ts->chip.dev = dev;