[AF_RXRPC]: Make it possible to merely try to cancel timers from a module

Export try_to_del_timer_sync() for use by the AF_RXRPC module.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

kernel/timer.c

@@ -505,6 +505,8 @@ out:
 	return ret;
 }
 
+EXPORT_SYMBOL(try_to_del_timer_sync);
+
 /**
  * del_timer_sync - deactivate a timer and wait for the handler to finish.
  * @timer: the timer to be deactivated