ide: fix generic_ide_suspend/resume Oops

This patch fixes a regresion introduced by commit 0998d063 (device-core: Ensure
drvdata = NULL when no driver is bound).

Suspend oopses in generic_ide_suspend() because dev_get_drvdata()
returns NULL (dev->p->driver_data == NULL) and this function is not
prepared for this.

Fix is based on Alan Stern's suggestion.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/ide/ide-pm.c

@@ -4,7 +4,7 @@
 
 int generic_ide_suspend(struct device *dev, pm_message_t mesg)
 {
-	ide_drive_t *drive = dev_get_drvdata(dev);
+	ide_drive_t *drive = to_ide_device(dev);
 	ide_drive_t *pair = ide_get_pair_dev(drive);
 	ide_hwif_t *hwif = drive->hwif;
 	struct request *rq;
@@ -40,7 +40,7 @@ int generic_ide_suspend(struct device *dev, pm_message_t mesg)
 
 int generic_ide_resume(struct device *dev)
 {
-	ide_drive_t *drive = dev_get_drvdata(dev);
+	ide_drive_t *drive = to_ide_device(dev);
 	ide_drive_t *pair = ide_get_pair_dev(drive);
 	ide_hwif_t *hwif = drive->hwif;
 	struct request *rq;