When ata device IDENTIFY failed, the ata device status is ATA_DEV_UNKNOWN. The
libata reported like:

[113518.620433] ata5.00: qc timeout (cmd 0xec)
[113518.653646] ata5.00: failed to IDENTIFY (I/O error, err_mask=0x4)

But libsas verifies the device status by ata_dev_disabled(), which skipped
ATA_DEV_UNKNOWN. This will make libsas think the ata device probing succeed
the device cannot be actually brought up. And even the new bcast of this
device will be considered as flutter and will not probe this device again.

Change ata_dev_disabled() to !ata_dev_enabled() so that libsas can deal with
this if the ata device probe failed. New bcasts can let us try to probe the
device again and bring it up if it is fine to IDENTIFY.
Tested-by: Zhou Yupeng <zhouyupeng1@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
CC: John Garry <john.garry@huawei.com>
CC: Johannes Thumshirn <jthumshirn@suse.de>
CC: Ewan Milne <emilne@redhat.com>
CC: Christoph Hellwig <hch@lst.de>
CC: Tomas Henzl <thenzl@redhat.com>
CC: Dan Williams <dan.j.williams@intel.com>
CC: Hannes Reinecke <hare@suse.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>