IPVS: Change sock_create_kernel() to __sock_create()

The recent netns changes omitted to change
sock_create_kernel() to __sock_create() in ip_vs_sync.c

The effect of this is that the interface will be selected in the
root-namespace, from my point of view it's a major bug.

Reported-by: Hans Schillstrom <hans@schillstrom.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>