ata: libahci: do not complain in case of deferred probe

Retrieving PHYs can defer the probe, do not spawn an error when
-EPROBE_DEFER is returned, it is normal behavior.

Fixes: b1a9edbd

 ("ata: libahci: allow to use multiple PHYs")
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>