rv: Let the reactors take care of buffers

Each RV monitor has one static buffer to send to the reactors. If multiple
errors are detected simultaneously, the one buffer could be overwritten.

Instead, leave it to the reactors to handle buffering.

Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>