net: hns3: split function hns3_nic_get_stats64()

mainline inclusion
from mainline-master
commit 8469b645
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4M1HB
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8469b645c9a1



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Function hns3_nic_get_stats64() is a bit too long. So add a
new function hns3_fetch_stats() to simplify code and improve
code readability.

Signed-off-by: Yufeng Mo <moyufeng@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Yongxin Li <liyongxin1@huawei.com>
Signed-off-by: Junxin Chen <chenjunxin1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>