scsi: lpfc: Fix coverity errors on NULL pointer checks

Coverity flagged several scenarios where checking of null pointer values
wasn't consistent.

Fix the code to that be consistent on checking.

Link: https://lore.kernel.org/r/20190922035906.10977-12-jsmart2021@gmail.com
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>