IPVS: Allow compilation with CONFIG_SYSCTL disabled

This is a rather naieve approach to allowing PVS to compile with
CONFIG_SYSCTL disabled.  I am working on a more comprehensive patch which
will remove compilation of all sysctl-related IPVS code when CONFIG_SYSCTL
is disabled.

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Hans Schillstrom <hans@schillstrom.com>
Tested-by: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>