device: Don't process link events anymore in device user specific callback handlers

Set link_state for all device types via the device_set_link API as all devices are registered
in the device tree list making it possible to always get the device via device_get.
The decice link state parameter will now actually reflect the corresponding kernel device
carrier state in all cases.
Before this change a vlan/macvlan device could still have link_state enabled if an interface
was brought down; this was the case when the parent vlan/macvlan device was still enabled as
the netlink link_state event would be dropped for vlan/macvlan devices due to keep_link_state
in the function cb_rtnl_event.

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>