bonding: make alb_send_learning_packets() use upper dev list

Currently, if there are vlans on top of bond, alb_send_learning_packets()
will never send LPs from the bond itself (i.e. untagged), which might leave
untagged clients unupdated.

Also, the 'circular vlan' logic (i.e. update only MAX_LP_BURST vlans at a
time, and save the last vlan for the next update) is really suboptimal - in
case of lots of vlans it will take a lot of time to update every vlan. It
is also never called in any hot path and sends only a few small packets -
thus the optimization by itself is useless.

So remove the whole current_alb_vlan/MAX_LP_BURST logic from
alb_send_learning_packets(). Instead, we'll first send a packet untagged
and then traverse the upper dev list, sending a tagged packet for each vlan
found. Also, remove the MAX_LP_BURST define - we already don't need it.

CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>