libata: update ata_dev_init_params()

Update ata_dev_init_params() such that it doesn't disable port directly but return with appropriate error mask on failure. This is preparation for splitting ata_dev_identify(). Note that this patch changes behavior of dev_init_params failure such that only failing devices are taken offline not the whole port. This change is intended.

Signed-off-by Tejun Heo <[email protected]>