qemu-bridge-helper: force usage of a very high MAC address for the bridge

qemu-bridge-helper: force usage of a very high MAC address for the bridge

Linux uses the lowest enslaved MAC address as the MAC address of
the bridge.  Set MAC address to a high value so that it does not
affect the MAC address of the bridge.

Changing the MAC address of the bridge could cause a few seconds
of network downtime.

Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1363971468-21154-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
(cherry picked from commit 226ecabfbd410c7b2041385ea4b6f083a09ce8a2)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>