scsi: lpfc: Add simple unlikely optimizations to reduce NVME latency

While performing code review, several relatively simple optimizations can
be done in the fast path.

Add these optimizations (unlikely designators).

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>