libata: drop ata_dev_select() from ata_dev_read_id

There is no reason to issue device select in read_id, it will be done
by ops->qc_issue() when IDENTIFY[_PACKET] is issued via
ata_exec_internal().

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