bridge: reset IPCB in br_parse_ip_options

Commit 462fb2af9788a82 (bridge : Sanitize skb before it enters the IP
stack), missed one IPCB init before calling ip_options_compile()

Thanks to Scot Doyle for his tests and bug reports.

Reported-by: Scot Doyle <lkml@scotdoyle.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>
Acked-by: Bandan Das <bandan.das@stratus.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Cc: Jan Lübbe <jluebbe@debian.org>
Signed-off-by: David S. Miller <davem@davemloft.net>