Instead of having two dsa_ds_find_port_dn (which returns a bool) and
dsa_dst_find_port_dn (which returns a switch) functions, provide a more
explicit dsa_tree_find_port_by_node function which returns a matching
port.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>