Documentation/rtla: Fix duplicate text about timerlat tracer

Documentation/rtla: Fix duplicate text about timerlat tracer

A passage about how the timerlat tracer outputs information is included
in both common_timerlat_description.rst and rtla-timerlat.rst, leading
it to be displayed twice in the rtla-timerlat page.

Remove the duplicate passage from rtla-timerlat.rst.

Fixes: 29380d4055e5 ("rtla: Add rtla timerlat documentation")
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
Reviewed-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250311114936.148012-2-tglozar@redhat.com