bonding: when cloning a MAC use NET_ADDR_STOLEN

A simple semantic change, when a slave's MAC is cloned by the bond
master then set addr_assign_type to NET_ADDR_STOLEN instead of
NET_ADDR_SET. Also use bond_set_dev_addr() in BOND_FOM_ACTIVE mode
to change the bond's MAC address because the assign_type has to be
set properly.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>