libata: disable pdev on all suspend events

libata used disable pdev only on PM_EVENT_SUSPEND while re-enable pdev
unconditionally.  This was okay before ref-counted pdev enable update
but it now makes the pdev pinned after swsusp cycle (enabled twice but
disabled only once) and devres sanity check whines about it.

Fix it by unconditionally disabling pdev on all suspend events.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>