tools/rv: Do not skip idle in trace

Currently, the userspace RV tool skips trace events triggered by the RV
tool itself, this can be changed by passing the parameter -s, which sets
the variable config_my_pid to 0 (instead of the tool's PID).
This has the side effect of skipping events generated by idle (PID 0).

Set config_my_pid to -1 (an invalid pid) to avoid skipping idle.

Cc: Nam Cao <namcao@linutronix.de>
Cc: Tomas Glozar <tglozar@redhat.com>
Cc: Juri Lelli <jlelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Link: https://lore.kernel.org/20250723161240.194860-2-gmonaco@redhat.com


Fixes: 6d60f896 ("tools/rv: Add in-kernel monitor interface")
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>