dev: Constify `ifname' parameter to device_up_and_running()

The parameter `ifname' to device_up_and_running() is never modified
inside the function, thus mark it as const.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
ioops: Constify `name' parameter to tun_open_or_die()

The parameter `name' to tun_open_or_die() is never modified
inside the function, thus mark it as const.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>