This adds APIs to trigger create, delete, interface up and interface down commands on bridge interface. It uses following IOCTLs for sending command to linux kernel: Add bridge iface: SIOCBRADDBR Remove bridge iface: SIOCBRDELBR Mark iface up/down: SIOCGIFFLAGS CRs-Fixed: 2080924 Change-Id: I3d34dc16e9ca82dc4b550cbc83fa4120c80ad54c