net: dsa: felix: remove redundant assignment in felix_8021q_cpu_port_deinit

Due to an apparently incorrect conflict resolution on my part in commit
54c31984 ("net: mscc: ocelot: enforce FDB isolation when
VLAN-unaware"), "ocelot->ports[port]->is_dsa_8021q_cpu = false" was
supposed to be replaced by "ocelot_port_unset_dsa_8021q_cpu(ocelot, port)"
which does the same thing, and more. But now we have both, so the direct
assignment is redundant. Remove it.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>