libata: add CONFIG_PM to libata core layer

Conditionalize all PM related stuff in libata core layer using
CONFIG_PM.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 00a9a6c..6cc817a 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -510,6 +510,7 @@
 	}
 }
 
+#ifdef CONFIG_PM
 /**
  *	ata_scsi_device_suspend - suspend ATA device associated with sdev
  *	@sdev: the SCSI device to suspend
@@ -634,6 +635,7 @@
 	sdev->sdev_gendev.power.power_state = PMSG_ON;
 	return 0;
 }
+#endif /* CONFIG_PM */
 
 /**
  *	ata_to_sense_error - convert ATA error to SCSI error