Clear LinkProperties on interface removed.

When an interface is removed, all netlink events for that
interface are lost, because netd will no longer be able to
resolve the ifindex in the netlink event to an interface name,
and it only communicates to the framework events that include an
interface name.

This can cause us to end up with stale IP addresses if, for
example, wlan0 is removed because we switch wifi back from AP
mode to STA mode when exiting tethering. The presence of stale
IPv4 addresses can in turn lead us to miss a provisioning
notification because we already think we have an IPv4 address.

Change-Id: Ib64559a5a4fa261f483760b69fa7996314e7cc17