alias : Fix interface aliased on top of a static interface not getting active

alias : Fix interface aliased on top of a static interface not getting active

An interfaces referring to a static interface is not getting active when doing a network
reload or ifup.
The problem is triggered by alias_set_device which is not clearing the pending update
(mostly a null device due to the previous down event) when the same device is set as the
current device via alias_notify_device.
As a result alias_set_device_state when called will overwrite the device with an invalid
pending device meaning the interface will not be set available anymore and thus will
stay down.

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