[SCSI] sd: update sd to use the new pm callbacks

Update sd driver to use the callbacks defined in dev_pm_ops.

sd_freeze is NULL, the bus level callback has taken care of quiescing
the device so there should be nothing needs to be done here.
Consequently, sd_thaw is not needed here either.

suspend, poweroff and runtime suspend share the same routine sd_suspend,
which will sync flush and then stop the drive, this is the same as before.

resume, restore and runtime resume share the same routine sd_resume,
which will start the drive by putting it into active power state, this
is also the same as before.

Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>