scsi: lpfc: Reduce time spent in IRQ for received NVME commands

Removed unnecessary bzero of context area. Due to size of sg list, added
a substantial delay and played havoc on cpu caches.

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