bridge: fix state reporting when port is disabled

Now we have:
eth0: link *down*
br0: port 1(eth0) entered *forwarding* state

br_log_state(p) should be called *after* p->state is set
to BR_STATE_DISABLED.

Reported-by: Zilvinas Valinskas <zilvinas@wilibox.com>
Signed-off-by: Paulius Zaleckas <paulius.zaleckas@gmail.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>