watchdog: imx2_wdt: add device tree probe support

Adds device tree probe support for imx2_wdt driver.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt

+* Freescale i.MX Watchdog Timer (WDT) Controller
+
+Required properties:
+- compatible : Should be "fsl,<soc>-wdt"
+- reg : Should contain WDT registers location and length
+- interrupts : Should contain WDT interrupt
+
+Examples:
+
+wdt@73f98000 {
+	compatible = "fsl,imx51-wdt", "fsl,imx21-wdt";
+	reg = <0x73f98000 0x4000>;
+	interrupts = <58>;
+};

drivers/watchdog/imx2_wdt.c

@@ -329,12 +329,18 @@ static void imx2_wdt_shutdown(struct platform_device *pdev)
 	}
 }
 
+static const struct of_device_id imx2_wdt_dt_ids[] = {
+	{ .compatible = "fsl,imx21-wdt", },
+	{ /* sentinel */ }
+};
+
 static struct platform_driver imx2_wdt_driver = {
 	.remove		= __exit_p(imx2_wdt_remove),
 	.shutdown	= imx2_wdt_shutdown,
 	.driver		= {
 		.name	= DRIVER_NAME,
 		.owner	= THIS_MODULE,
+		.of_match_table = imx2_wdt_dt_ids,
 	},
 };