net: hns3: get rss_size_max from configuration but not hardcode

Add configuration for rss_size_max in hdev but not hardcode it.

Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Mingguang Qu <qumingguang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>