Fengguang reported:
   net/core/netpoll.c: In function 'netpoll_setup':
   net/core/netpoll.c:1049:6: warning: 'err' may be used uninitialized in this function [-Wmaybe-uninitialized]
in !CONFIG_IPV6 case, we may error out without initializing
'err'.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 #else
                        np_err(np, "IPv6 is not supported %s, aborting\n",
                               np->dev_name);
+                       err = -EINVAL;
                        goto put;
 #endif
                }