net: hsr: sync hw addr of slave2 according to slave1 hw addr on PRP

net: hsr: sync hw addr of slave2 according to slave1 hw addr on PRP

In order to work properly PRP requires slave1 and slave2 to share the
same MAC address. To ease the configuration process on userspace tools,
sync the slave2 MAC address with slave1. In addition, when deleting the
port from the list, restore the original MAC address.

Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>
Signed-off-by: David S. Miller <davem@davemloft.net>