rtla: Automatically move rtla to a house-keeping cpu

When the user sets -c <cpu-list> try to move rtla out of the <cpu-list>,
even without an -H option. This is useful to avoid having rtla
interfering with the workload.

This works by removing <cpu-list> from rtla's current affinity.

If rtla fails to move itself away it is not that of a problem as this
is an automatic measure.

Link: https://lkml.kernel.org/r/c54304d90c777310fb85a3e658d1449173759aab.1686066600.git.bristot@kernel.org

Cc: William White <chwhite@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>