rtla/timerlat_bpf: Allow resuming tracing

rtla/timerlat_bpf: Allow resuming tracing

Currently, rtla-timerlat BPF program uses a global variable stored in a
.bss section to store whether tracing has been stopped.

Move the information to a separate map, so that it is easily writable
from userspace, and add a function that clears the value, resuming
tracing after it has been stopped.

Cc: John Kacur <jkacur@redhat.com>
Cc: Luis Goncalves <lgoncalv@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Chang Yin <cyin@redhat.com>
Cc: Costa Shulyupin <costa.shul@redhat.com>
Cc: Crystal Wood <crwood@redhat.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/20250626123405.1496931-4-tglozar@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>