scsi: lpfc: Limit amount of work processed in IRQ

Various oops being seen on being in the ISR too long and cpu lockups,
when under heavy load.

The amount of work being posted off of completion queues kept the ISR
running almost all the time

Correct the issue by limiting the amount of work per iteration.

[mkp: typo]

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