ixgbe_service_task() is calling ixgbe_reinit_locked() without
the rtnl_lock being held. This is because it is being called
from a worker thread and not a rtnl netlink or dcbnl path.

Add rtnl_{un}lock() semantics. I found this during code review.
Signed-off-by: NJohn Fastabend <john.r.fastabend@intel.com>
Tested-by: NPhil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>