net/ipv6: Initialise msg_control_is_user

do_ipv6_setsockopt() makes use of struct msghdr::msg_control in the
IPV6_2292PKTOPTIONS case. Make sure to initialise
msg_control_is_user accordingly.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ipv6_sockglue.c

@@ -716,6 +716,7 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 			goto done;
 
 		msg.msg_controllen = optlen;
+		msg.msg_control_is_user = false;
 		msg.msg_control = (void *)(opt+1);
 		ipc6.opt = opt;