fix(bridge): pick up MAC from another interface

This avoids the OPERSTATE unknown when the bridge is brought up but the
members are not ready yet.

This will make OPERSTATE to down, enabling us to wait until we have
brought up completely all the members.

Signed-off-by: Raito Bezarius <masterancpp@gmail.com>

pkgs/liminix-tools/networking/default.nix

@@ -9,6 +9,7 @@
     ip link set up dev ${ifname}
     (in_outputs ${name}
      echo ${ifname} > ifname
+     cat /sys/class/net/${ifname}/address > ether
     )
   '';
 }