[PATCH] libata-ncq: pass ata_scsi_translate() return value to SCSI midlayer

ata_scsi_translate() will need to return SCSI_ML_QUEUE_DEVICE_BUSY to
achieve exlusion between NCQ and non-NCQ commands or among non-NCQ
commands.  Pass its return value upward to SCSI midlayer.

Signed-off-by: Tejun Heo <htejun@gmail.com>