mlxsw: spectrum: Report port type according to operational speed

In case port isn't operational we shouldn't report the port type, but
instead return PORT_OTHER. This is consistent with most other drivers
that return PORT_OTHER when media type can't be determined.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>