renode: Add Renode overlays for selected tests

Tune quantum parameter for selected kernel tests
targetting the HiFive Unleashed platform.

Those tests require higher fidelity of the virtual
time flow which is achievable on multi-core platforms
in Renode by reducing the quantum.

Signed-off-by: Jan Malek <jmalek@internships.antmicro.com>
Signed-off-by: Mateusz Holenko <mholenko@antmicro.com>