net: prestera: add support for port range filters

This adds support for port-range rules:

  $ tc qdisc add ... clsact
  $ tc filter add ... flower ... src_port <PMIN>-<PMAX> ...

Co-developed-by: Volodymyr Mytnyk <volodymyr.mytnyk@plvision.eu>
Signed-off-by: Volodymyr Mytnyk <volodymyr.mytnyk@plvision.eu>
Signed-off-by: Maksym Glubokiy <maksym.glubokiy@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>