net: dsa: remove port masks

Now that DSA core provides port types, there is no need to keep this
information at the switch level. This is a static information that is
part of a DSA core dsa_port structure. Remove them.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>