TetherController - print iface names in bpf info

Test:
  adb shell dumpsys netd --short | sed -rn '/^  TetherController$/,/^ *Log:$/p'

  TetherController
    Forwarding requests: Tethering
    DNS: netId 100 servers [198.224.173.135, 198.224.174.135, 2001:4888:68:ff00:608:d::, 2001:4888:61:ff00:604:d::]
    dnsmasq PID: 4395
    Interface pairs:
      rmnet_data2 -> rndis0 ACTIVE

    BPF ingress map: iif(iface) v6addr -> oif(iface) srcmac dstmac ethertype [pmtu]
      12(rmnet_data2) 2600:1010:b009:76c8:b0fc:57ff:fe6e:8cc4 -> 33(rndis0) be:b2:04:f9:1a:98 b2:fc:57:6e:8c:c4 86dd [1500]
    BPF stats (downlink): iif(iface) -> packets bytes errors
      12(rmnet_data2) -> 1 104 0
    BPF limit: iif(iface) -> bytes
      12(rmnet_data2) -> 9223372036854775807

Bug: 150736748
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I19148e4b079ac1fd2e8a5bf983bd9d8aa1dc4305