Need to propagate MTU changes that the bridge does to it's pseudo interface
up to others. There ends up being a double call to br_min_mtu() but that's
harmless.

Cleans up the EXPORT_SYMBOLS including dev_change_flags which is used by vlan.
Shouldn't be basing exports on kernel config options like this.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@redhat.com>