perftune.py: make RPS CPU set to be a full CPU set
perftune.py: make RPS CPU set to be a full CPU set

Enable RPS on all requested CPUs (or all present CPUs if
cpu_mask is not given).

This makes networking more efficient for applications that are bound
to IRQ CPUs.

Fixes #818

Signed-off-by: Vlad Zolotarov <976c0f8d0852ed6439ad273880b400a75a7c41d0@scylladb.com>
Message-Id: <20210324230703.1013177-1-976c0f8d0852ed6439ad273880b400a75a7c41d0@scylladb.com>

cloudius-systems/seastar,scylladb/seastar,cloudius-systems/seastar,avikivity/seastar,syuu1228/seastar,scylladb/seastar,scylladb/seastar,cloudius-systems/seastar,avikivity/seastar,syuu1228/seastar,avikivity/seastar,syuu1228/seastar