rtla: Refactor save_trace_to_file

rtla: Refactor save_trace_to_file

The functions osnoise_hist_main(), osnoise_top_main(),
timerlat_hist_main(), and timerlat_top_main() are lengthy and contain
duplicated code.

Refactor by consolidating the duplicate lines into the
save_trace_to_file() function.

Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: John Kacur <jkacur@redhat.com>
Cc: "Luis Claudio R. Goncalves" <lgoncalv@redhat.com>
Cc: Eder Zulian <ezulian@redhat.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/20250219115138.406075-1-costa.shul@redhat.com
Signed-off-by: Costa Shulyupin <costa.shul@redhat.com>
Reviewed-by: Tomas Glozar <tglozar@redhat.com>
Tested-by: Tomas Glozar <tglozar@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>