scsi: lpfc: Use *_pool_zalloc rather than *_pool_alloc

Use *_pool_zalloc rather than *_pool_alloc followed by memset with 0.

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Acked-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>