mfd: Guard tc3589x PM methods with CONFIG_PM_SLEEP

Guard PM methods with CONFIG_PM_SLEEP and get rid of some unneeded #ifdefs.
This fixes below build warnings:

  CC      drivers/mfd/tc3589x.o
drivers/mfd/tc3589x.c:361:12: warning: 'tc3589x_suspend' defined but not used [-Wunused-function]
drivers/mfd/tc3589x.c:375:12: warning: 'tc3589x_resume' defined but not used [-Wunused-function]

SIMPLE_DEV_PM_OPS already defines constant dev_pm_ops, thus also fix
'duplicate const' sparse warning.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/tc3589x.c

@@ -357,7 +357,7 @@ static int __devexit tc3589x_remove(struct i2c_client *client)
 	return 0;
 }
 
-#ifdef CONFIG_PM
+#ifdef CONFIG_PM_SLEEP
 static int tc3589x_suspend(struct device *dev)
 {
 	struct tc3589x *tc3589x = dev_get_drvdata(dev);
@@ -385,11 +385,10 @@ static int tc3589x_resume(struct device *dev)
 
 	return ret;
 }
-
-static const SIMPLE_DEV_PM_OPS(tc3589x_dev_pm_ops, tc3589x_suspend,
-						tc3589x_resume);
 #endif
 
+static SIMPLE_DEV_PM_OPS(tc3589x_dev_pm_ops, tc3589x_suspend, tc3589x_resume);
+
 static const struct i2c_device_id tc3589x_id[] = {
 	{ "tc3589x", 24 },
 	{ }
@@ -399,9 +398,7 @@ MODULE_DEVICE_TABLE(i2c, tc3589x_id);
 static struct i2c_driver tc3589x_driver = {
 	.driver.name	= "tc3589x",
 	.driver.owner	= THIS_MODULE,
-#ifdef CONFIG_PM
 	.driver.pm	= &tc3589x_dev_pm_ops,
-#endif
 	.probe		= tc3589x_probe,
 	.remove		= __devexit_p(tc3589x_remove),
 	.id_table	= tc3589x_id,