models: Reorder bonding options so the mode is applied first

The option lacp_rate, for instance, is exclusive to the mode
802.3ad (4) and changing it under the default mode balance-rr (0)
results in "Operation not permitted" error.

Guard against this by ordering the mode first (and the rest of
options alphabetically).

Change-Id: I61553c05b34f10d8e81c41fbfdbc448d8fe120a9
Signed-off-by: Ondřej Svoboda <osvoboda@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/27572
Reviewed-by: Antoni Segura Puimedon <asegurap@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>