netfilter: ipv6: nf_defrag: Kill frag queue

Release the frag queue if an error in IPv6 frag header is detected
so that it does not interfere with IPv6 frag reassembly and timeouts.

CRs-Fixed: 2168587
Change-Id: I4eed2e7ce383fddde2818880e3795ada9ed7fcb5
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>