int scsi_internal_device_unblock (struct scsi_device * sdev);
Called by scsi lld's or the midlayer to restart the device queue for the previously suspended scsi device. Called from interrupt or normal process context.
Returns zero if successful or error if not.
This routine transitions the device to the SDEV_RUNNING state (which must be a legal transition) allowing the midlayer to goose the queue for this device. This routine assumes the host_lock is held upon entry.