[libata] PM callbacks should be conditionally compiled on CONFIG_PM_SLEEP

This will fix warnings like following when CONFIG_PM_SLEEP is not set:

        warning: 'xxx_suspend' defined but not used [-Wunused-function]
        warning: 'xxx_resume' defined but not used [-Wunused-function]

Because
	SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)

Only references the callbacks on CONFIG_PM_SLEEP (instead of CONFIG_PM).

Cc: Viresh Kumar <viresh.linux@gmail.com>
Cc: linux-ide@vger.kernel.org
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/ata/pata_arasan_cf.c b/drivers/ata/pata_arasan_cf.c
index 71111f2..371fd2c 100644
--- a/drivers/ata/pata_arasan_cf.c
+++ b/drivers/ata/pata_arasan_cf.c
@@ -914,7 +914,7 @@
 	return 0;
 }
 
-#ifdef CONFIG_PM
+#ifdef CONFIG_PM_SLEEP
 static int arasan_cf_suspend(struct device *dev)
 {
 	struct ata_host *host = dev_get_drvdata(dev);