rxrpc: remove unused static variables

The rxrpc_security_methods and rxrpc_security_sem user has been removed
in 648af7fc ("rxrpc: Absorb the rxkad security module"). This was
noticed by kbuild test robot for the -RT tree but is also true for !RT.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/security.c

@@ -19,9 +19,6 @@
 #include <keys/rxrpc-type.h>
 #include "ar-internal.h"
 
-static LIST_HEAD(rxrpc_security_methods);
-static DECLARE_RWSEM(rxrpc_security_sem);
-
 static const struct rxrpc_security *rxrpc_security_types[] = {
 	[RXRPC_SECURITY_NONE]	= &rxrpc_no_security,
 #ifdef CONFIG_RXKAD