net: hns3: split out hclge_fd_check_ether_tuple()

For readability and maintainability, this patch separates the
handling part of each flow type in hclge_fd_check_ether_tuple()
into standalone functions.

Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>