[SCSI] lpfc: use SCSI_MLQUEUE_TARGET_BUSY when catching the rport transition race

We do want to call right back into the queuecommand during the race,
so we can just use SCSI_MLQUEUE_TARGET_BUSY.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: James Smart <James.Smart@Emulex.Com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>