daemon: fixup refcounting in close callback handling

daemon: fixup refcounting in close callback handling

remoteDispatchConnectCloseCallbackRegister introduced in
f484310a has problems. It refcounts network client object and in case of NOOP
driver operations for registering/unregistering close callback (any driver
except for vz) nobody will unref it later. As a result, client connection
will not be disposed and driver connection will not be closed.

The fix is easy. We don't need to refcount at all. We don't get a dangling
pointer because in remoteClientFreeFunc, which is called
upon disposing this network client object, we unregister the close
callback.

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>
Signed-off-by: Erik Skultety <eskultet@redhat.com>