bonding: use rtnl_deref in bond_change_rx_flags()

As it's always called with RTNL held, via dev_set_allmulti/promiscuity.
Also, remove the wrong comment.

CC: Jay Vosburgh <j.vosburgh@gmail.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Veaceslav Falico <vfalico@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/bonding/bond_main.c
Simple merge