ofctl_v1_2: fix pep8

ryu/lib/ofctl_v1_2.py:444:15: E127 continuation line over-indented for visual indent

Signed-off-by: TAKAHASHI Minoru <takahashi.minoru7@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
ofctl_v1_2: fix errors of get_flow_stats

following match fields caused an exception at get_flow_stats command:

  ipv6_nd_sll, ipv6_nd_tll

this patch fixes this problem.

Signed-off-by: TAKAHASHI Minoru <takahashi.minoru7@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>