ipv6: fix possible mem leaks in ipv6_make_skb()

ip6_setup_cork() might return an error, while memory allocations have
been done and must be rolled back.

Change-Id: Icd789cb74e1950b73e3fab37773b5fe22222b0a1
Fixes: 6422398c ("ipv6: introduce ipv6_make_skb")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Vlad Yasevich <vyasevich@gmail.com>
Reported-by: Mike Maloney <maloney@google.com>
Acked-by: Mike Maloney <maloney@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Git-commit: 862c03ee1deb7e19e0f9931682e0294ecd1fcaf9
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


[tejaswit@codeaurora.org : resolved merge conflict ]
Signed-off-by: Tejaswi Tanikella <tejaswit@codeaurora.org>