Support the addition and deletion of Flow Director filters.

Supported fields: src-ip, dst-ip, src-port, dst-port
Supported flow-types: tcp4, udp4, sctp4, ipv4
Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>