scsi: lpfc: Use memset_startat() helper

Use memset_startat() helper to simplify the code, no functional changes in
this patch.

Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Link: https://lore.kernel.org/r/20221111074310.132125-1-xiujianfeng@huawei.com


Reviewed-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>