inet6: Remove inet6_destroy_sock() in sk->sk_prot->destroy().

inet6: Remove inet6_destroy_sock() in sk->sk_prot->destroy().

After commit d38afeec26ed ("tcp/udp: Call inet6_destroy_sock()
in IPv6 sk->sk_destruct()."), we call inet6_destroy_sock() in
sk->sk_destruct() by setting inet6_sock_destruct() to it to make
sure we do not leak inet6-specific resources.

Now we can remove unnecessary inet6_destroy_sock() calls in
sk->sk_prot->destroy().

DCCP and SCTP have their own sk->sk_destruct() function, so we
change them separately in the following patches.

Signed-off-by: Kuniyuki Iwashima <[email protected]>
Reviewed-by: Matthieu Baerts <[email protected]>
Signed-off-by: David S. Miller <[email protected]>