net: hns3: fix hns3_cae_pfc_storm.h missing header guard problem

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

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This patch adds missing header guard to the hns3_cae_pfc_storm.h.

Signed-off-by: Yonglong Liu <liuyonglong@huawei.com>
Reviewed-by: li yongxin <liyongxin1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>