rtla/osnoise: Add support to adjust the tracing_thresh

rtla/osnoise: Add support to adjust the tracing_thresh

osnoise uses the tracing_thresh parameter to define the delta between
two reads of the time to be considered a noise.

Add support to get and set the tracing_thresh from osnoise tools.

Link: https://lkml.kernel.org/r/715ad2a53fd40e41bab8c3f1214c1a94e12fb595.1646247211.git.bristot@kernel.org
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>