ata: expose ncq_enable_prio sysfs attribute only on NCQ capable hosts

There is no point in exposing ncq_enable_prio sysfs attribute for
devices on PATA and non-NCQ capable SATA hosts so:

* remove dev_attr_ncq_prio_enable from ata_common_sdev_attrs[]

* add ata_ncq_sdev_attrs[]

* update ATA_NCQ_SHT() macro to use ata_ncq_sdev_attrs[]

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>