staging: batman: remove all rcu head initializations

Remove all rcu head inits. We don't care about the RCU head state before
passing it to call_rcu() anyway. Only leave the "on_stack" variants so
debugobjects can keep track of objects on stack.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Cc: Marek Lindner <lindner_marek@yahoo.de>
Cc: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>