ethernet: s2io: Use skb_put_data() instead of skb_put/memcpy pair

Use skb_put_data() instead of skb_put() and memcpy(), which is shorter
and clear. Drop the tmp variable that is not needed any more.

Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
Link: https://lore.kernel.org/r/20220927022802.16050-1-shangxiaojing@huawei.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>