net: hns3: split out hclge_get_fd_rule_info()

hclge_get_fd_rule_info() is bloated, this patch separates
it into several standalone functions for readability and
maintainability.

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>