[docker] set RA and RIO for Backbone interface (#988)
[docker] set RA and RIO for Backbone interface (#988)

The docker by default set up RIO and RA for the eth0 interface. It can
be change only during docker build time.  This commit's changes allow
to setup RA and RIO based on backbone interface.
openthread/ot-br-posix,openthread/borderrouter,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter,openthread/ot-br-posix,openthread/ot-br-posix,openthread/borderrouter,openthread/borderrouter,openthread/ot-br-posix