Introduce a dsa_is_normal_port helper to check if a given port is a
normal user port as opposed to a CPU port or DSA link.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>