net: marvell: prestera: Fix deinit sequence for router

* Add missed call prestera_router_fini in prestera_switch_fini
* Add prestera_router_hw_fini, which verify lists are empty

Fixes: 69204174 ("net: marvell: prestera: Add prestera router infra")
Signed-off-by: Yevhen Orlov <yevhen.orlov@plvision.eu>
Link: https://lore.kernel.org/r/20220111011129.5457-1-yevhen.orlov@plvision.eu


Signed-off-by: Jakub Kicinski <kuba@kernel.org>