move wm8400-regulator's probe function to .devinit.text

A pointer to wm8400_regulator_probe is passed to the core via
platform_driver_register and so the function must not disappear when the
.init sections are discarded.  Otherwise (if also having HOTPLUG=y)
unbinding and binding a device to the driver via sysfs will result in an
oops as does a device being registered late.

An alternative to this patch is using platform_driver_probe instead of
platform_driver_register plus removing the pointer to the probe function
from the struct platform_driver.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

drivers/regulator/wm8400-regulator.c

@@ -289,7 +289,7 @@ static struct regulator_desc regulators[] = {
 	},
 };
 
-static int __init wm8400_regulator_probe(struct platform_device *pdev)
+static int __devinit wm8400_regulator_probe(struct platform_device *pdev)
 {
 	struct regulator_dev *rdev;