pinctrl: coh901: add device tree support

This makes it possible to probe the COH901 pinctrl driver from
the device tree, and assigned the device tree node in the
gpio_chip so we can look up cross-references from the device
tree. Start grabbing the per-port (bank) IRQs by index instead
of by name so we don't have to look up the IRQs by name going
forward.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/gpio/gpio-stericsson-coh901.txt

+ST-Ericsson COH 901 571/3 GPIO controller
+
+Required properties:
+- compatible: Compatible property value should be "stericsson,gpio-coh901"
+- reg: Physical base address of the controller and length of memory mapped
+  region.
+- interrupts: the 0...n interrupts assigned to the different GPIO ports/banks.

drivers/pinctrl/pinctrl-coh901.c

@@ -773,8 +773,7 @@ static int __init u300_gpio_probe(struct platform_device *pdev)
 		port->number = portno;
 		port->gpio = gpio;
 
-		port->irq = platform_get_irq_byname(pdev,
-						    port->name);
+		port->irq = platform_get_irq(pdev, portno);
 
 		dev_dbg(gpio->dev, "register IRQ %d for port %s\n", port->irq,
 			port->name);
@@ -811,6 +810,9 @@ static int __init u300_gpio_probe(struct platform_device *pdev)
 	}
 	dev_dbg(gpio->dev, "initialized %d GPIO ports\n", portno);
 
+#ifdef CONFIG_OF_GPIO
+	gpio->chip.of_node = pdev->dev.of_node;
+#endif
 	err = gpiochip_add(&gpio->chip);
 	if (err) {
 		dev_err(gpio->dev, "unable to add gpiochip: %d\n", err);
@@ -864,9 +866,15 @@ static int __exit u300_gpio_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct of_device_id u300_gpio_match[] = {
+	{ .compatible = "stericsson,gpio-coh901" },
+	{},
+};
+
 static struct platform_driver u300_gpio_driver = {
 	.driver		= {
 		.name	= "u300-gpio",
+		.of_match_table = u300_gpio_match,
 	},
 	.remove		= __exit_p(u300_gpio_remove),
 };