Migrate timer handling (removed in 6.13) and netdev dummy initialization
(removed in 6.16) to new methods with guards to not break older kernels.
This resolves compilation errors due to missing del_timer_sync(),
from_timer() and init_dummy_netdev().
Signed-off-by: Stefan Kalscheuer <stefan@stklcode.de>
Link: https://github.com/openwrt/openwrt/pull/22775
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
