net: hns3: add header file hns3_ethtoo.h

mainline inclusion
from mainline-master
commit edb40bbc
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I46N7D
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=edb40bbc17eb589beb3cbd672d341e1505d6cdb1



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Add a new file hns3_ethtool.h, and move struct type definitions from
hns3_ethtool.c to hns3_ethtool.h.

Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Yongxin Li <liyongxin1@huawei.com>
Signed-off-by: Junxin Chen <chenjunxin1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>