rtc: ds1286: Initialize drvdata before registering device

Commit f44f7f96a20 ("RTC: Initialize kernel state from RTC") uncovered
an issue in a number of RTC drivers, where the drivers call
rtc_device_register before initializing the device or platform drvdata.

This frequently results in null pointer dereferences when the
rtc_device_register immediately makes use of the rtc device, calling
rtc_read_alarm.

The solution is to ensure the drvdata is initialized prior to registering
the rtc device.

CC: Wolfram Sang <w.sang@pengutronix.de>
CC: Alessandro Zummo <a.zummo@towertech.it>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: rtc-linux@googlegroups.com
Signed-off-by: John Stultz <john.stultz@linaro.org>

drivers/rtc/rtc-ds1286.c

@@ -355,6 +355,7 @@ static int __devinit ds1286_probe(struct platform_device *pdev)
 		goto out;
 	}
 	spin_lock_init(&priv->lock);
+	platform_set_drvdata(pdev, priv);
 	rtc = rtc_device_register("ds1286", &pdev->dev,
 				  &ds1286_ops, THIS_MODULE);
 	if (IS_ERR(rtc)) {
@@ -362,7 +363,6 @@ static int __devinit ds1286_probe(struct platform_device *pdev)
 		goto out;
 	}
 	priv->rtc = rtc;
-	platform_set_drvdata(pdev, priv);
 	return 0;
 
 out: